FWD – The engine is usually directly over the front driving wheels. Example – Honda Civic.

Good – Due to fewer parts and less energy travel distance, FWD is by design more fuel efficient and more work efficient than RWD. Weight of the car is typically less, as well, since there is no need for a driveshaft. Also, in inclement weather, FWD has better traction than RWD and MR configurations since the majority of the weight is over the driving wheels which pull the car. Also, since the engine is in the front, the air that is “cut” by the car can be easily used to keep the engine cool.

Bad – Since FWD uses CV joints to prevent control loss during steering, the engine should not be made too powerful. A 600 horsepower engine will like break CV joints very easily. Also, during hard steering, if the throttle is applied too much, FWD cars go into a front wheel slide. Steering becomes very wide as the car’s tendency to go straight will take over.

RWD – Engine in front of the driver, driving wheels in the back of the driver. Example – Chevrolet Corvette.

Good – Because the rear wheels do not need to steer the car, and because the rear differentials tend to be stronger, more powerful engines can be used in RWD cars than FWD cars. A 600 horsepower engine is not as likely to break a differential or a U joint as it would be a CV joint. Steering traction and acceleration traction are more balanced in RWD than FWD. Since the engine is in the front, the air that the car passes through can help keep the engine cool.

Bad – Lack of weight over the rear wheels lessens traction for the driving wheels. However, this can be used to your advantage in strange situations. For example, my mom’s ’97 TransAm had a wide turning radius, and was difficult to get through many local parking garages, so I would spin the rear wheels a little to push the back end out and straighten it out when I needed it. The driveline in RWD is generally heavier than FWD and MR, and more power is lost through the transmission and driveshaft than what is lost in FWD and MR configurations. Therefore, by design, RWD is less fuel efficient and less work efficient than FWD or MR.

MR – To me, MR does not include cars that have the engine behind the front wheels but in front of the driver. MR, defined by me, would have the engine in the rear, usually directly over the rear drive wheels. Example – The original Volkswagen Beetle, and also most transit buses.

Good – Because the rear wheels do not need to steer the car, and because the rear differentials tend to be stronger, more powerful engines can be used, in MR than FWD. A 600 horsepower engine is not as likely to break a differential as it would a CV joint. Steering traction and acceleration traction are more balanced in MR than FWD. Since the engine is in the back, MR configurations have better rear wheel traction during acceleration. It is this traction (combined with light weight) that allows the Porsche 911 Turbo beat a Viper in the 1/4 mile. Acceleration out of a corner can be started sooner due to the combined frictional and inertial forces. Due to a lighter driveline and a shorter energy path, MR configurations by design are the most efficient of the configurations.

Bad – Because MR configurations tend to have more weight in the rear, the tail end can push during hard braking and cornering. I felt this tendency to push even when I test drove a Smart ForTwo, which is a very small car with very little power. Also, since the engine is in the rear, cooling is a more difficult task. Often, cars with very large and very powerful engines in the rear have very large and powerful radiators in the front. This is because there is much less airflow getting to the engine, so liquid cooling tends to be more robust.

AWD – All four wheels drive the car. I’m going to lump 4WD in this as well, because the same basic physical principles apply. AWD usually has the engine in the front. There are some AWD cars with engines in the rear, but those are usually exotics. Example – Nissan GT-R (front engine) and Lamborghini Diablo (rear engine).

Good – Best traction of all, since all four wheels have the ability to exert frictional forces to move the car. AWDs can also have rather powerful engines, at least compared to FWD, since the rear wheels tend to take more of the acceleration force than the front wheels. Since the engine is usually in the front, cooling is generally an easy task.

Bad – Lose traction in AWD, and you lose complete control. An engine that is too powerful can cause all four wheels to spin, and the force of inertia will be greater than the force of friction during cornering, which will send the vehicle in a straight line and possibly spinning. AWD systems also have many more moving parts than any other configuration, so there is more probability of mechanical failure. Since AWDs have more parts, they are generally heavier. And, since there is more driveline, there is more energy lost in AWD than any other configuration. Therefore, by design, AWD is the least fuel efficient and work efficient configuration.

Just a disclaimer, when I say “by design”, I mean essentially “assuming all other things are equal”. If only the driveline changed, but the engine and everything else stayed the same, the most efficient configuration would be MR, then FWD, then RWD, then AWD. But that’s not to say that there are no efficient AWD or RWD setups. In fact, AWD and RWD can be more efficient, but it takes different materials for the driveline and for the car. But then, comparing a Subaru AWD and a 2004 Nissan Quest (FWD) really isn’t keeping all things equal.

Fuel efficiency comes from many factors, of which driveline is only one. Drag, horsepower, displacement, tire friction, weight, transmission, driving habits, driving location, etc., all affect fuel efficiency, which is why there are RWD vehicles that are more efficient that FWD vehicles. But again, keeping all other factors EXACTLY the same, the lighter weight and shorter energy path physically dictate that FWD will be more efficient than RWD.

Work efficiency means that it takes less energy to do the same amount of (or more) work. An example of this is Apple’s switch from PPC to Intel processors. By doing this switch, Apple was able to increase work efficiency. The newer Intel processors were 2X to 3X faster than the PPC processors, and yet they used far less electricity to run.

Agreed, the problem as always with the Big 3 is that the minute they get a bright idea… they don’t think outside of the box in such a way to make sure that their plans don’t get foiled by outside options/alternatives.

My case in point… GM with the Impala getting axed from Zeta. Can you say, beyond stupid? You already have the platform, you have people that WANT RWD vehicles. That isn’t to say that they all had to be V8 powered vehicles. In fact, considering the successes Toyota has had with the Prius… the writing should’ve been on the wall long ago even before gas prices went through the roof.

True, the other cars out there weren’t selling in volume as hybrids but then again… gas wasn’t $4.50 a gallon at the time many were introduced and those that were spending money on big cars were going for mongo huge SUV’s that got 1/2 of what even a decently equipped RWD sedan with an adequate V6 or reasonable V8 would get. Given the option of a large RWD sedan with even base mpg of 20 and a high of 30 much less 30/40mpg and good performance… sales are going to happen as long as it looks good and is solidly built. The market wasn’t rabid for hybrid sedans because those that wanted hybrids bought them to be chic, largely because gas was cheap enough that people just didn’t care and would’ve kept on buying gas at $2.80-3.40 a gallon and coped with it.

Now that gas prices are escalating… hybrids, turbos, and diesels should be in the R&D phase for anything and everything you can muster. That doesn’t mean you scrap your platforms you had in the works, change your product planning, and add another 4 years to your development cycles! GM, Ford, and Chrysler have a penchant for milking significant product updates, per car/line, for up to 8-12 years whereas the Japanese imports refresh by at least 4, if not clean sheet redesign. Is it any wonder that a car’s sales stall after you’ve milked it for 8-12 years and half of those with a desire for one already have one and the rest are wanting something fresh/new?

Look at rear transaxles much like some sports cars. The engine power is leveraged more effectively to the rear wheels instead of being lost in translation through the drive shaft. Balance will be better and power transfer will be more effective. Also building transmissions that don’t EAT 100hp going to the wheels would be nice.

Efficiency is definitely key… and you can build an efficient RWD driveline. You can build economical RWD vehicles, it’s not like in the early 60′s GM and Ford and Chrysler didn’t do just that. There was numerous small cars like Chevy II’s and Falcon’s and the old Barracuda’s and the like powered by straight-6′s. GM should’ve been planning to launch Zeta with V6′s all along, and when the economy shifted and gas prices soared… much as they did during the gas crisis (and caught the Big 3 with their pants down then too) in the 70′s; they should’ve been able to adapt and keep on trucking vs. park projects people want and bail out in favor of returning to the same old utilitarian crap they’ve degenerated to selling over the years.

Performance and character are what is going to help save and set the Big 3 apart, it was *ALWAYS* what would help save the Big 3. The more they attempt to copy the character (i.e. either European-style styling or more of a utilitarian vs. charismatic character) of the imports, the less in-tune with Americana they are. If you look at what saved Harley Davidson in motorcycles… it wasn’t building multi-valve 4-banger or even Goldwing-style V6′s. It was sticking to the script that brought them success. Even if they were to change from their current engine lineup, if Harley does *ANYTHING* to desecrate the character of their bikes… they will fail. In a trio of companies that have had wild product styling and bold styling over the years, building their own take on an Accord, Civic, etc. is not going to cut it. You are not going to win people by being a poseur and copying the segment leader, people will take the original and leave the copies to the side. Yet, if GM or Ford or Chrysler were to bust out a small RWD car with 4 and turbo 4-banger power that was in line with the old Chevy II and Falcon and Barracuda in terms of character… drifting would immediately draw in a whole new crowd and an Americana image that it currently lacks. Even the Solstice/Sky isn’t enough there… largely because they still look Imported.

Efficient RWD cars, esp. with the drifting craze (if GM, Ford, or Chrysler built a small 4-place RWD coupe/sedan about the size of a Civic or even a G6/Aura/Malibu with a rash of engine options the things would sell like bananas), that rely on capable performance engines and newer technologies like hybrid drivelines, turbo V6′s (anyone remember the success GM had with the Buick Grand National, GNX, and T-Type Buicks?), clean-burning diesels, and even Flex-fuel technology are the way for them to go. It allows them a way to build vehicles with character, but to do so in ways that fit the economy and rising fuel costs, and yet a car that allows people to have their cake (economy) and eat it too (burn the wheels off for fun). Hybrid’s need not be utilitarian appliances… even Toyota has shown that agenda/theme with the Toyota FT-HS (not that it’s necessarily attractive but the idea itself does have credence). Just because gas prices spike doesn’t mean that everyone is going to turn into a hardcore environmentalist… but it might shift the economics towards a more practical performance car.

Use lighter materials, higher quality steel, carbon fiber (in the cabin and other non-structural components, more aluminum. Take some of what was learned (if anything) from constantly boosting the F-150 over the last 20 years to make large cars and make them practical and appealing.

The reality is for the last 30 years the Big 3 have faltered due to mismanagement. It’s not the UAW, not incompetent workers (other than executive staff). It’s strictly from excess bean counting, knee-jerk reactions, and floundering on how to shift product from original plans to an alternative. Rather than use flexible plans like Toyota, Honda, et al. the Big 3 start a project and the minute something blows up in their face… they all fall over theirselves, scrap projects/plans, change agendas, and add another 3-4 years of red tape to their production cycle as they attempt to reinvent the wheel.

ADAPT DAMN IT… ADAPT!

Chrysler doesn’t need to scrap the LX, it doesn’t need to create a new FWD mid-size platform or source another one (i.e. snag the Altima from Nissan). If it wants to do anything, call up Daimler and source a Diesel engine family. Call up GM and work on adding Flex-fuel options to their engine platforms so that as gas prices rise and low-cost grass-based E85 can be produced in quantity enough, that they can take advantage (even with the mileage hit per gallon). Call up Toyota or Honda and source Hybrid technologies.

Then… here’s the hard one for the executive staff at Chrysler.

Retrofit the technologies to your existing platforms, and drop them into the R&D plan for each and every one of your future products in the pipeline. I don’t care what the car is… being a green carmaker, a car like the Prius will have it’s place for a time but eventually once the industry adopts the technology, that “chic” nature of being an early adopter is going to wear and eventually people will buy cars because of styling vs. the “Hey look, I’m an environmentalist, I drive a Prius.” stereotyping that they play after.

GM, Ford… it’s the same script. You’ve got plenty of great platforms in the mix… use ‘em. Don’t sit there like a doubting Thomas hemming and hawing on what to do next. For every day you ponder whether or not to follow through with your plans that you so neatly contrived… you waste one more day in getting new product to market that will help dig you out of the hole. While small cars are selling, it’s only because of the improved mileage and the fact they’re already present and available. If you don’t think there’s a need for an efficient larger car… you’re totally misguided and incompetent and might as well bail out now.

Oh and another tip… instead of decontenting and using cheaper interior materials to try to significantly undercut your competition in the same market (i.e. try to sell a midsize sedan for $5k less than a competitor vs. build a car with better materials and try to compete by having a car that’s as good, styled better, and with more character/appeal), build to be competitive. GM has shown with the Malibu that they can design a truly great interior, but… the materials are still questioned. That tells me that as great a step-up as the Malibu is, GM still has not gotten the memo that the car should be built to last long-term. If GM can cut costs using cheaper plastics on the interior, I still am a huge skeptic (from past experiences being a GM owner) that they can’t do the same underneath. The long-term standing on whether the Malibu is a success or failure is in large part based on whether electrical gremlins or part failures over the course of ownership kick the feet out from it’s success mid-stride and render it as another failure when there was so much promise to start with.

GM is not alone in this arena (i.e. pointing at Chrysler and to *SOME* degree Ford on some cars, they’ve gotten better on some too… i.e. Fusion, Milan, Edge, Taurus/500, etc.) but it’s still the same reality. It’s like GM with the Astra vs. Cobalt. Given the choice, I’d take the Astra every day despite the fact that the Euro->Dollar relationship is killing it. Build the Astra, as-is, with no changes at a U.S. Plant and it’d slay the Cobalt and be competitive. Especially if you managed to build an Opel/Vauxhall Astra VXR-equivalent as an Astra Redline. That said, I think GM could do better to think outside of the box a bit more with the next rung of small cars. Much as the Volt’s styling is kind of intriguing… I still think GM would be better served to making a car that is multipurpose and not strictly a hybrid or plug-in hybrid with it. Give it the same styling as the concept and toss it on a small version of GM’s RWD Alpha platform with a well-built turbo-4 with a hybrid option and I think it’d be better than trying to spawn a $40k hybrid sedan and try to build a market for it against the Fit’s, Corolla’s, etc. Granted, with GM building the Cruze… I’m not sure that there’s a need there, but judging by the shots of the Cruze I’ve seen, I don’t know that there’s a need for the Cruze in general. LoL

All that sad, it should not be hard to roll out a a large or full-sized car that gets around 40mpg highway and the low the mid 30s in the city.

AMEN! Couldn’t be said better no matter how you want to spin it. With the push towards Eco-Boost at Ford, the talk of high power normally aspirated and turbo V6′s even at GM, the stage is set. The market isn’t going to demand that their cars are the segment leader in mpg’s and take that in sacrifice of a car that’s well designed, built, and that is appealing. The Prius is *NOT* the most economical car out there, it’s just economical enough to appeal to those that want one. It’s sized right, has the right interior volume. That said, the Honda Civic is likely a better buy. The Honda Fit, on mileage, is as good or better than the Prius on mileage and has ample room inside. That said… the Prius is the darling.

I don’t dislike the Prius, think it’s great for what it is, but we don’t live in a one size fits all, one product image fits all universe. There’s muscle car people that won’t be caught dead in a Prius (or even a Fit despite it’s clearly the boy racer of the 2) but give ‘em a bad to the bone 4-door sedan tricked out to look like the old RWD Impala SS of yore graphically that gets 30-40 mpg using a turbo V6, and you’ll have the second coming of the Grand National if you can put the proper image/creds behind it to back it up. Enough efficiency, when driven calmly, to do some long-distance vacationing but enough mustard to be driven in anger and leave fuel thirsty vehicle owners in bewilderment in a stop light drag race when they get their butt handed to ‘em. Just because gas prices go up doesn’t mean people aren’t going to want fun cars. They might not burn the tires off of the car everywhere but they’re still going to want to punch it every now and then. Someone is going to have to meet that demand, it’s not going to go away.

FORD Build it and build it right. Get some practice in and make a stretched four door version on the Mustang Platform. A bit smaller, less expensive, it’s here NOW, and you would get a faster turn-around on Mustang parts.

Bah, just move to the Falcon platform and get it over with. A heavily revised lightweight next-gen Falcon driveline using a lightened version of the platform with an Eco-Boost engine option, maybe even a hi-po Eco-Boost, base V6′s and maybe even turbo 4′s depending on what cars you build off of it, maybe a hybrid version, and maybe even a *VERY* limited edition high-po compact V8 for the muscle car fanatic that can’t let go of the V8 rumble and has expendable cash to burn on fuel… you’re set. Use it to underpin a car the size of the Crown Vic (or better, maybe Avalon-sized as the packaging on the Crown Vic isn’t exactly “stupendous”), maybe even look at using it for the Taurus (despite all perception that it likely will be on the next Mazda 6 platform), a new Mustang, maybe a rebirth of the 4-place RWD T-bird (or if another 2-seater, can use it for that and build a new coupe… maybe a new Torino, maybe a U.S. Falcon), etc.

Just do it already!

Agreed… and to GM and Chrysler, that goes for you both as well. If Lutz and company can’t bring this to market too, they’ve failed and the beancounters have won again at the expense of GM as a car company into the future. If Cerberus can’t inject life into Chrysler’s productline by more than redesigning a Versa or Sentra or sourcing Chery or Great Wall-built cars… they’re still screwed. They all are.

You should probably read the F/econ rating for RWD, FWD cars going through the 1980s, 1990s, till now. The only way that argument works is if you ignore the fact that anything DETROIT made in the 1980s that was RWD had a bigger, more powerful, engine in it. Truthfully F/econ for RWDs has improved to the point that you can get a 300+hp RWD car that actually as good or better with gas than a less powerful FWD in the same class. Good luck not having to check European cars on that.

DETROIT erroneously opted to go with trucks and SUVs going into the 1990s and spend AS LITTLE MONEY AS POSSIBLE, developing cars. FWD is cheaper and easier to develop. better F/econ was the direct result of using smaller less powerful engines not mechanical efficiency. If you look back at smaller cars in the 1960s and 1970s, still RWD but they got better F/econ. Relative to the technology of the day it is not had to see a car like the Maverick getting upwards of 35mpg even as a RWD. The 1990′s Thunderbird, a large coupe, could make over 30mpg and this was before F/econ was a real consideration. Even with a V8 the car could still top 25mpg. Most FWDs that size could not do better enough to matter.

It is very hard to compare FWD cars and RWD on the basis of F/econ because they never have the same engine yet differing drivetrains. FWD cars are typically much less powerful than RWD cars. Ultimately, there is not reason for a RWD to be as good on gas as a FWD.

I have also pointed to some step FORD or any automaker could take to insure good gas mileage in comment #21. But I did miss good aerodynamics, with FORD was aces with int he 1990s hence the Thunderbird’s great, for the time, F/econ even with a V8.

The issue is the amount of work the company is will to put into their product. Having to play catch up after decades of trashing perfectly good cars out of production, will result in higher initial expense but that is FORD’s fault. If they had kept up their cars, half as well as they did their trucks and SUVs, FORD would be almost invincible.

beatusmongus- I’d like to look at these physics your talking about.

Fact of the matter is, RWD is more efficient than front wheel drive, it’s just a matter of drivetrain components and space.

A4- Both are getting axed and one model will replace both of them.

The Sedan is a bit more expensive but the coupe is roughly equal to the Mustang, challenger, and later the Camaro in price. Besides HYUNDAI is decidedly aiming the Genesis Sedan further upmarket.

@Blakkarr,
I don’t know if I’d call the Genesis affordable. It starts where G8 tops out. Either way its the exception to the rule. Right now the most affordable RWD you can get is a pickup-truck.

German makes could learn from the F150 and its ilk as well. A 7-series only weighs 200lbs less than a Silverado Crew Cab.

You forgot the Hyundai Genesis sedan and coupe. But aside form that I see that.

Look at rear transaxles much like some sports cars. The engine power is leveraged more effectively to the rear wheels instead of being lost in translation through the drive shaft. Balance will be better and power transfer will be more effective. Also building transmissions that don’t EAT 100hp going to the wheels would be nice.

Use lighter materials, higher quality steel, carbon fiber (in the cabin and other non-structural components, more aluminum. Take some of what was learned (if anything) from constantly boosting the F-150 over the last 20 years to make large cars and make them practical and appealing.

All that sad, it should not be hard to roll out a a large or full-sized car that gets around 40mpg highway and the low the mid 30s in the city.

FORD Build it and build it right. Get some practice in and make a stretched four door version on the Mustang Platform. A bit smaller, less expensive, it’s here NOW, and you would get a faster turn-around on Mustang parts.

Just do it already!

@olds307,
This would not be a suitable replacement for the Crown Vic. The Vic is a body-on-frame sedan which gives it unique characteristics. If Ford kept it up to date it could be towing 6,000lbs while not being an SUV. A few suspension upgrades, a reskin, and the 5.4L Triton would have made the Vic a very compelling SUV alternative.