New Hardtop for 3 Series

BMW released pictures of the fourth generation 3 Series convertible today, more than two months before its debut at the North American International Auto Show (NAIAS) in Detroit. As with so many other modern day convertibles, BMW has opted to fit the 3 Series with a retractable hardtop instead of a fabric top. According to the company, the three-piece roof is made of lightweight steel and opens in just 22 seconds.

The car definitely looks good judging from the photos, but fitting the car with a hardtop rather than a conventional fabric top has added 400 pounds of unsprung weight over the coupe version. BMW claims the new roof structure will make the cabin of the new 3 series quieter at speed, and that the platform will retain the torsional strength and rigidity to keep the car's handling at levels BMW customers have come to expect.

To offset the weight added from the metal roof, BMW has added plastic side front fenders which weigh 50 per cent less than conventional steel panels. The new top is also claimed to improve visibility to the rear by 38 per cent and the rear side windows are also 30 per cent larger than the outgoing car.

In the US, two versions will be available: the 335i and the 328i. The 330i features twin turbochargers and an intercooler said to produce 300hp at 5,800 rpm and 300 lb-ft of torque at 1,400 – 5,000rpm. Claimed acceleration times to 60 mph are 5.5 seconds for the six-speed manual, and 5.7 seconds for the six-speed Steptronic automatic transmission. Standard cars will see their top speed electronically-limited to 130mph while top speed on vehicles fitted with the Sport Package will be governed at 150mph.

The lesser 328i features a 230hp 3.0 litre inline six-cylinder engine with Valvetronic technology and aluminum/magnesium construction. The horsepower peak is acheived at 6,500rpm and 200 lb-ft of torque is available at 2,750 rpm. BMW claims acceleration from 0 to 60mph can be accomplished in 6.7 seconds for the six-speed manual and in 7.2 seconds with the six-speed automatic. Like the 335i, the 328i is limited to 130 mph or 150 mph if equipped with the Sport Package.

The new six-speed automatic transmission available on both models is claimed to be quicker and more responsive thanks to the hydraulic control system and torque converter which ensure reaction times that are 40% faster than conventional automatics. Gear change timing has been almost halved in this model, while The torque converter clutch connects the engine more directly to enhance performance, engine response, and fuel economy.

Optional gearshift paddles on the steering wheel can also be ticked on the options list on models with the Sport package and automatic transmission. These paddles can be activated directly at any time - even if the gear selector lever is in Drive making it easy to acheive spontaneous performance.

The new convertible features a double-pivot McPherson strut-type aluminum suspension in front and a five-link independent rear suspension, with 17-inch alloy wheels wrapped in 225/45R17 runflat tyres. Even with a complete loss of pressure in one tire, the vehicle can continue to be driven for up to 150 miles at 50 miles per hour to get to the nearest service station. The Tire Pressure Monitor watches the pressures in each tire and will warn the driver as soon as the pressure drops more than 25 percent below the optimum level.
In the interior, BMW has increased shoulder room at the rear by 3.15 inches and elbow room by 4.72 inches. The company has also fitted special leather treated with Sun Reflective technology on the seat upholstery and on the armrests to prevent body contact with excessively hot surfaces. This new leather treatment is able to reduce surface temperatures on dark interior colours by up to 68 °F, and also offers advantages on light-colored upholstery, where the heating effect of sunshine is less severe developed for the seating upholstery. Modified color pigments serve to reflect the infra-red radiation by the sun, very effectively preventing excessive temperatures on the seat surfaces otherwise encountered in weather that would be perfect for open-air motoring.