Honda is planning a three-prong transmission strategy for its upcoming hybrid vehicles, a move that underscores the difficulties it has encountered attempting to cater to both its enthusiast base and a burgeoning market for high-mpg vehicles.
Honda's hybrid line will go in three directions – a one-motor variant hooked up to a seven-speed dual clutch transmission (named i-DCD) for smaller cars (Fit hybrid-size vehicle), a two-motor system with a CVT for mainstream high-mpg models (Accord Hybrid and Plug-In Hybrid) and a three-motor system mated to all-wheel-drive and the i-DCD for the company's high-end models ( Acura RLX and NSX). Notably, Honda is now branding all of its gasoline-electricity models as “Sport Hybrids,” a marketing move presumably designed to connect with drivers put off by the detached experience most hybrids offer.
Leftlane was on hand at Honda's research and development center outside of Tokyo to briefly sample all three powertrains – plus the automaker's upcoming rear-wheel steering system - in test mule vehicles, two of which will hit the North American market in 2013.
Four cylinders, two transmissions
Mated to a new 1.5-liter four-cylinder gas engine, the one motor hybrid system is a unique rethink of Honda's small car strategy. Instead of the CVTs that typically transmit power to the wheels, the automaker's new seven-speed i-DCD is designed to provide a more engaging – and familiar – driving experience.
Our tests were limited to a current generation Japanese market Honda Fit test mule (Honda won't say just where the new powertrain will first arrive, but the next-generation Fit and Civic seem likely). We found engagement of the transmission to be particularly smooth, although shifts are not as rapid-fire as the DSG unit fitted to the new Volkswagen Jetta Hybrid. Compared to balky dual clutch units used by some rivals in non-hybrid compacts – think Ford Focus and Dodge Dart – the Honda unit provided nearly conventional automatic-style shifting. The dual clutch can deliver EV-only driving at startup and during low to medium speed cruising thanks to a clutch that disengages the gas engine entirely.
But the advantages, Honda says, are in its fuel economy and its ability to increase energy regeneration during deceleration. Making the most of the 1.5-liter's power band, the dual clutch increases fuel economy by about 30 percent over a CVT.
However, CVTs aren't entirely a thing of the past, Honda says. The company's new two-motor system will arrive early next year in the North American-market Accord Hybrid and Accord Plug-In Hybrid. Here, the CVT couples with a 2.4-liter four-cylinder, a pair of built-in electric motors and a lock-up clutch for three driving modes – EV, gas engine and traditional hybrid.
Aside from a slight gruffness as the engine approaches higher revs, the CVT is generally well behaved in its operation. Acceleration feels linear and free of the “elastic band” effect that used to afflict CVTs.
Previewing Acura's new RLX
Our favorite vehicles to sample were a pair of last-generation Honda Accords that hid the 2014 Acura RLX's upcoming all-wheel-drive powertrain and front-wheel-drive suspension with rear wheel steering.
Hidden behind the old Accord body, the Super Handling all-wheel-drive (or SH-AWD) model's three-motor hybrid was mated to a 3.5-liter V6, the seven-speed dual clutch (with its own electric drive motor) and a pair of electric motors at the rear to individually apportion torque between the right and left rear wheels. Despite its name, the system has little in common with the SH-AWD of the current, slow-selling Acura RL.
Despite the old body (and good looking 19-inch wheels), the Accord test mule we drove was positively 21st century. The seven-speed dual clutch transmission was set only to a sport setting (a normal mode will be the default), which gave it firm shifts and rev blimps on downshifting. We didn't get to sample the car in normal mode.
Pushed hard into a corner on Honda's ultra-smooth test track, the mule was confident and stable. Torque transition between the rear wheels was essentially unnoticeable, but a heads-up display projects an image of how much power is headed to each of the four wheels. Though the screen could prove a little distracting in production models, it was useful during our evaluation.
Honda promises four-cylinder fuel economy and V8-level power delivery. We'll have to wait for the EPA figures for the former, but the lithium-ion battery pack and electric motor do provide credibility to the eight-cylinder performance comparison.
Next up was the Accord mule with the world's first independent rear-steer system, which will be fitted only to the front-wheel-drive base model version of the RLX. Capable of adjusting the rear wheels' toe – the angle at which they “steer” - the system has several advantages: It aids high speed cornering and lane changes, it decreases low speed turning radii and, notably, it increases stability during braking.
We found all three of Honda's claims to be true, especially at low velocities, where the Accord mule felt uncannily nimble. At first, the rear end felt a bit “loose” while navigating a tight corner, but we soon adapted to the system. During braking, the mule was arrow-straight and predictable.
With their rear torque-transitioning motors, all-wheel-drive RLXs realize most of the Precision All Wheel Steer system's advantages on their own, so the system is front drive-exclusive, but we think a version of the system will make great sense if it is eventually brought down to Honda's most mainstream model, the Accord.
What's it all mean?
Though we'll have to wait for a full evaluation of the new technologies in production models, Honda's decision to simultaneously focus and expand its hybrid lineup strikes us as a valuable strategy.
We're particularly excited about the seven-speed dual clutch unit, which Honda will also use on its gas-only models. Perhaps the hybrid future is bright after all.
Photos courtesy Honda.