German manufacturer Alpina is preparing to launch its own take on the new BMW 3-series with an all-new range of B3 Biturbo models.

First up will be a new B3 saloon, which is scheduled for a launch at the Geneva motor show next March. Touring, coupé and convertible models will follow the B3 saloon over the next couple of years.

The B3, spied here in light disguise on hot-weather testing in southern Europe, gets a series of subtle styling changes over the BMW 335i saloon on which it is based. These include a lip spoiler and tweaks to the lower section of the bumper at the front, bespoke alloy wheel designs, a small boot spoiler and quad exhaust outlets.

Under the bonnet is a revised twin-turbo 3.0-litre straight six with similar power and torque figures to those of the current B3 S Biturbo.

Power is likely to be around 400bhp and torque 400lb ft, three-quarters of which will be available from just 1300rpm, preserving Alpina’s famed low-end grunt.

Rear-wheel drive will be standard, with all-wheel drive optional on saloon, Touring and coupé models, although there’s a question mark over the convertible, because it is not yet known whether BMW will offer right-hook versions of the convertible with all-wheel drive.

New D3 diesel models are also in the launch plan, but they are not expected until later in 2013 at the earliest.