The B4 BiTurbo is based on the BMW 435i, from 2016 onwards on the BMW 440i. The B4 BiTurbo replaces the convertible and coupe versions of the B3 S BiTurbo.

In line with the new naming conventions at BMW, from the F30-series onwards the Cabrio and Coupe versions of the B3 BiTurbo are named B4 BiTurbo.

In December 2013, at the Tokyo motorshow, the B4 BiTurbo was introduced as Coupe version. At the same time, the 4WD version – the B4 Allrad – was introduced, it is available only as Coupe.

The premiere of the Cabrio version of the B4 BiTurbo was at the Geneva motorshow in March 2014.

In October 2016, the B4 Coupe Allrad was presented as the first Alpina model officially available in China.

In March 2017, the B4 BiTurbo was replaced by the B4 S BiTurbo.

The B4 BiTurbo engine is based on the BMW 435i engine, which has been modified to 410hp and 600Nm.

The stainless steel exhaust system was developed together with Akrapovič. It features exhaust system sound control with Drive Performance Control.

The only available gearbox is the 8-speed Sport-Automatic transmission (ZF 8HP70) with Switchtronic.

Optionally, a Drexler limited slip differential is available.

The B4 BiTurbo has adaptive M sport suspension with electronically adjustable dampers, performance springs, bump stops and stabilisers. The suspension is modified with Alpina settings.

Wheels are 20-inch Alpina Classic with 245/30 and 265/30 Michelin Pilot Super Sport tires. For winter conditions, 19-inch Alpina Classic wheels are available with 245/35 Michelin Pilot Alpin PA3 tires.

The suspension features a strut brace and adjustments to camber, toe-in and elastokinematics.

Brakes disks are 370x30mm front and 345x24mm rear with blue aluminum calipers (4-piston front, 2-piston rear) with Alpina lettering.

The B4 BiTurbo undergoes the same interior changes as usual with Alpina. Cluster gauges are custom Alpina with classic blue background combined with steering wheel trimmed in Lavalina leather. Additionally, interior trim is fine Alpina wood or piano lacquer with Alpina logos. A no-cost option are Alpina badges in the seats. Optionally, a custom interior in Lavalina leather can be ordered, as well as additional instruments mounted in the center airduct.

For the exterior, the changes are limited to an Alpina Type 994 frontspoiler and Alpina badges on the rear. The Coupe version has an Alpina Type 997 rearspoiler and the Cabrio version has an Alpina Type 998 rearspoiler. A non-cost option is the classic Alpina decor on sides of the car and frontspoiler. Available exterior colors include Alpina Blue and Alpina Green II.

Acceleration from 0-100kph is 4,2 seconds.

Topspeed is 301kph for the convertible and 303kph for the coupe version.