Intended as a surprise unveiling at the Los Angeles Auto Show, BMW has revealed the 2011 6-Series convertible.  However, for reasons unknown the drop-top never made it to the show. It's unfortunate given the importance of the sunny Californian market.

Drawing inspiration from the Concept 6-Series Coupe, the convertible has a long bonnet, a forward-slanted grille, xenon headlights, distinctive LED fog lights and 18-inch alloy wheels (19-inchers on the 650i). To reduce weight, BMW has retained the 6-Series' double buttress soft top which can be lowered in 19 seconds and raised in 24 seconds at speeds up to 25 mph (40 km/h).

Inside, the cabin mimics the previous 6-Series but there is a greater emphasis on material quality and driver-focused controls. Notable highlights include Dakota leather upholstery (Nappa leather with SunReflective Technology is optional) and a freestanding 10.2-inch iDrive display which can display e-mails via Bluetooth connection with a BlackBerry smartphone.

At launch, two engines will be available. The 640i uses a turbocharged 3.0-liter inline six-cylinder engine that produces 320 hp (239 kW / 324 PS) and 450 Nm (332 lb-ft) of torque. This allows the car to accelerate from 0-100 km/h in 5.7 seconds and hit an electronically limited top speed of 155 mph (250 km/h). In terms of efficiency, expect 35.8 mpg (imp) in the combined cycle and CO2 emissions of 185 g/km.

In the 650i, power is provided by a twin-turbo 4.4-liter V8 engine with 407 hp (304 kW / 413 PS) and 600 Nm (442 lb-ft) of torque. It enables the drop top to accelerate from 0-100 km/h in 5.0 seconds, before hitting an electronically limited 155 mph (250 km/h). Furthermore, it is expected to average a combined 26.4 mpg (imp) and emit 249 grams of CO2 per kilometer.

Regardless of what engine is selected, a six-speed manual is standard and eight-speed automatic is optional (some markets, such as the UK, will be automatic only).

To ensure the convertible handles like a proper BMW, engineers installed an advanced suspension which features an aluminum-intensive double wishbone front axle and a multi-link rear. Dynamic Damper Control is standard, but optional Active Roll Stabilization can further improve things to ensure flat and stable cornering. Additionally, an Integral Active Steering system is available. It combines the Active Steering system for the front axle with a new steerable rear axle which gives the 6-Series greater "high-speed stability and enhanced maneuverability for parking and city use."

Compared to its predecessor, the new 6-Series is 74mm longer, 39mm wider, and 9mm shorter. This results in a much needed increase in rear passenger room and a bigger boot which holds up to 350 liters of luggage (300 liters with the roof down).

The convertible will be launched in Europe in March and U.S. sales are slated to begin in the spring.  Prices to be announced at a later date.

Gallery: 2011 BMW 6-series Cabrio revealed [video]

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