Diesel models traditionally sell well for Alpina, being richer in torque and lighter on fuel than their higher-powered petrol siblings, and the fundamental recipe appears unchanged for the German firm's latest model.
In the D3 S, it benefits from Alpina’s larger intercoolers, a broader suite of improved cooling systems and revised mapping to make 350bhp and 538lb ft – figures up 15bhp and 22lb ft on the previous D3 – and achieve WLTP combined fuel economy of 37.2mpg.
By comparison, the 462bhp petrol B3 manages 28.8mpg, and therein lies the core appeal of the diesel Alpina 3 Series – not least because, with the B3's total of 516lb ft, the diesel's torque advantage is now fairly slim.
Because this engine is originally engineered by BMW to use a 48-volt starter-generator, the D3 S is also the first Alpina to feature an electrified powertrain. Smoother stop-start is one benefit of the system, and this should enhance refinement, but the mild-hybrid set-up is also able to contribute small amounts of instant torque for improved throttle response.
There are changes for the eight-speed ZF torque-converter automatic gearbox, although only in the form of software revisions to help it better withstand sustained high loads – for example while driving on the autobahn, where the new car will hit 170mph in saloon form and 168mph as the estate-bodied Touring.
Unsurprisingly, the D3 S is quicker all-out than its M340d cousin, which is limited to 155mph, although their 0-62mph times are identical, at 4.6sec for the saloon and 4.8sec for the estate.
Substantial work has also gone into the car’s four-wheel-drive chassis, which retains BMW's clutch-based xDrive torque-split between the axle but uses a new limited-slip differential at the rear and the same adaptive Alpina Sport suspension fitted to the B3.
There are also brand-specific Eibach springs, and the damper modes are tuned to deliver more of Alpina’s trademark ride quality. Additional negative camber for the front wheels should improve stability and steering feel, while forged wheels that collectively lessen unsprung mass by 14kg should improve steering response.
The other major chassis upgrade comes in the form of the brakes, which are carried over directly from the 205mph B5 Biturbo. In addition, lightweight, drilled composite brake discs are available.
Elsewhere, you'll find the usual Alpina hallmarks. These include subtle aerodynamic tweaks, oversized 20-spoke alloy wheels (now available up to 22in diameter) and, optionally, pinstripe decals. The deep, logo-emblazoned front spoiler and custom exhauast complete the major aesthetic additions.
Deliveries of the D3 S are due to start in November. While UK prices are still to be confirmed, in Germany they start at €70,500 (around £61,340) for the saloon and €71,900 (£62,550) for the estate.