The 1-Series Convertible is the drop-top version of BMW's least expensive car, the 1-Series Coupe. Despite its relatively low price point, the little drop-top doesn't disappoint in the realm of handling thanks to a host of components shared with the outgoing version of the legendary 3-Series. The 1-Series Convertible recently received a mild refresh that brought minor styling updates and BMW's single-turbo inline-six in place of the old twin-turbo unit.
In appearance, the 1-Series Convertible offers a pleasing combination of traditional BMW styling cues - like the familiar dual kidney-shaped grille - and the contemporary "flame styling" that BMW's designers are finally mastering.
The 128i Convertible recently received a revised lower front fascia with new foglights and an "air curtain" ducting system that smooths airflow by directing it from the lower intakes to the outside of the front wheels. Both the 128i and the 135i Convertibles make use of updated head- and tail-lights.
The 1-Series Convertible is powered by the same 3.0-liter inline six-cylinder engines of previous model 3-Series, with the naturally-aspirated 128i engine producing 230 horsepower and 200 lb-ft of torque and the turbocharged 135i engine producing 300 horsepower and 300 lb-ft of torque. Both engines have on-demand engine coolant pumps to improve fuel economy and increase power.
A recently added model is the 135is convertible, which is the most competent 1-series convertible to date (the discontinued, 340-horsepower 1-Series M Coupe that shared many components with the BMW M3 was never offered as a convertible). It is now the highest-performing 1-series in the range, getting a 20hp bump from the standard 135i.
Most drivers are likely to choose the six-speed manual transmission, the same satisfying performer as in the 3-Series, but a six-speed automatic is also available. The 135i accelerates to 60 mph in less than 5.3 seconds with top speed electronically limited to 155 mph. Focusing on a younger driver than other BMWs, the car makes a louder noise when producing this performance, a combination of less sound-deadening interior materials and a more audible exhaust.
The new 135is still uses the N55 inline-six, but it's upgraded to 320-horsepower and 317lb-ft of torque, gains of 20 and 17, respectively. It's also halfway to the 1-Series M Coupe's 340hp number. BMW promises to match fuel economy numbers to the less power turbo car as well.
The 135i Convertible comes equipped with M-inspired aero kit and larger rear spoiler for additional downforce. The optional Sports Suspension includes 18-inch wheels, performance tires, and a high-performance brake system with six-piston fixed calipers
at the front.
The 135is gets a unique sports exhaust, stiffer suspension, and unique, 18-inch alloy wheels. Another way to tell the new model apart from the lesser ones are high-gloss, black exterior accents as well. Both a six-speed manual and seven-speed double-clutch transmission are on offer, as is coupe equivalent.
First things first: BMW's controversial iDrive system comes only with the optional navigation system. The rest of the interior follows BMW tradition and includes galvanized pearl gloss surfaces on the interior door handles, glove compartment handle, the radio's rotary knobs, the knobs of the automatic air conditioning system, the (optional) iDrive controller and the ornamental trim strips on the steering wheel.
Leatherette is standard on all models with Boston Leather as an option. The Sport Package, a BMW staple, includes sport seats with enhanced bolsters. A 60/40 split-folding rear seat is standard.
The latest version of iDrive is equipped with six Programmable Memory Keys that allow the driver to program functions that are used particularly often such as navigation destinations, radio stations or specific telephone numbers. Touch-sensitive sensors on these buttons preview the function on the iDrive screen before the button is depressed.
Available and standard equipment on the 1-Series Convertible includes: Sirius satellite radio, HD radio, a premium sound system and Bluetooth interface. For simple and straightforward connection of an MP3 player, an auxiliary input jack is standard, and a USB port for direct control of an Apple iPod or iPhone media player is available as an option.
Six airbags come standard, including dual front airbags, side airbags integrated into the seats and side curtain airbags in the roof lining.
What Lies Beneath...The Sheetmetal
The rear wheel drive 1-Series Coupe has a sophisticated suspension system with an aluminum double-pivot front suspension and a five-link fully independent rear suspension in lightweight steel. Like all RWD BMWs, the 1-Series features 50/50 weight distribution. BMW's Dynamic Stability Control (DSC) also includes a Dynamic Traction Control (DTC) function that provides electronic intervention to prevent loss of vehicle control, but at a higher threshold before activation. Both DSC and DTC can be disabled entirely.
The DSC system on the 135i Convertible is designed specifically for performance-oriented driving. For instance, the accelerator pedal has a quicker response rate and electronic rear brake management is used to simulate a differential lock for stronger acceleration in turns. The rear differential features double-helical ball bearings for the first time, which reduces the amount of fluid required in the differential and reduces operating temperatures.
Active Steering, a variable ratio steering system exclusive to BMW, is optional. The double-pivot spring and strut front suspension is made largely of aluminum.
Those looking for a drop-top alternative to the 1-Series Convertible should consider the Audi TT Roadster, the Ford Mustang GT Convertible and the Nissan 370Z Roadster.