The B4 Bi-Turbo Cabrio is an evolution of the 435i.

German BMW tuner Alpina has pulled the sheet on the 2014 B4 Bi-Turbo Cabrio, a performance-focused convertible based on the recently-introduced BMW 4-Series Convertible. The B4 Bi-Turbo Cabrio debuted this week at the Geneva Motor Show.

Like its hardtop counterpart, the B4 Bi-Turbo is powered by a twin-turbocharged version of the 435i's 3.0-liter straight-six engine that sends 410 horsepower and 443 lb-ft. of torque to the rear wheels via an eight-speed automatic transmission. The coupe sprints from zero to 62 mph in 4.5 seconds - half a second faster than a regular-production 435i - and reaches an Autobahn-worthy top speed of 189 mph.

When driven conservatively, Alpina's latest coupe is capable of returning nearly 30 mpg in a mixed European cycle thanks in part to a standard start / stop system. A sport-tuned adaptive suspension helps improve handling, while upgraded brakes with aluminum calipers on all four corners and Michelin Pilot tires keep the extra power in check.

Drivers who want extra grip can order the car with a modified version of BMW's xDrive all-wheel drive system.

Outside, Alpina's latest coupe receives an aggressive front bumper characterized by a big air dam and a lip spoiler adorned with Alpina-specific decals. Wide multi-spoke alloy wheels help give the car a race-bred appearance.

Alpina lets buyers customize their car's interior by choosing from a long list of fabrics and colors. All B4s regardless of configuration come standard with leather upholstery, electric seats, xenon headlights, automatic climate control and rain-sensing wipers.

The Alpina B4 Bi-Turbo Cabrio will go on sale in select European countries next summer. Pricing information will be available closer to its launch.