Alpina is developing a new generation of its B4 based on the latest BMW 4-Series range, as evidenced by a prototype spotted in Germany.

While the last B4 used the 4-Series' coupe body style, the new one will use the more practical 4-Series Gran Coupe hatchback as the basis. This should make it more popular in the key markets of China and the U.S. (if it ends up here), where coupes tend to sell in low numbers.

The 4-Series Gran Coupe was revealed in June and the first examples are only just rolling into dealerships across the country. The Alpina version is at least a year away as development is at a very early stage. The only changes we spot on the prototype are the Alpina-style exhaust tips, new rear fascia, and possibly an Alpina brake package. More advanced prototypes should feature a new front fascia and side skirts.

Expect the mechanicals to match the setup used in the Alpina B3 based on the 3-Series. This means the powertrain of choice will be the 3.0-liter turbocharged inline-6 normally found in the M440i. Expect Alpina's version of the engine to deliver about 462 hp and 516 lb-ft of torque, versus the stock rating of 382 hp and 364 lb-ft. An 8-speed automatic and all-wheel drive should also form part of the package.

2023 BMW Alpina B4 Gran Coupe spy shots - Photo credit: S. Baldauf/SB-Medien

2023 BMW Alpina B4 Gran Coupe spy shots - Photo credit: S. Baldauf/SB-Medien

An Alpina D4 diesel may also be developed. Alpina offers a 3-Series-based D3 S diesel good for 350 hp and 538 lb-ft of torque.

Other upgrades typical of Alpina vehicles include sport-tuned suspension, improved aerodynamics, and the company's signature multi-spoke wheels.

It isn't clear whether the B4 will reach the U.S. There's the chance we might see it as BMW doesn't look to be planning an M4 Gran Coupe, meaning there wouldn't be any direct competition with a BMW model. Current Alpina offerings in the U.S. include the B7 (7-Series), XB7 (X7), and B8 Gran Coupe (8-Series Gran Coupe).

Stay tuned for updates as development continues.