Alpinaâ€™s sparky sports coupÃ© has broad-brush ability
Looking for a fast, comfy, 400bhp-plus coupÃ©? Lucky you. The choices are tasty: Mercedes-AMG C63,Â Audi RS5, BMW M4 â€“Â and now, to be a little bit different, Alpina B4 S Biturbo. And it’s more than just different.
This B4 SÂ replaces the old B4. It uses the M4â€™s straight-six-engined platform but adds a raft of changes, both visual and techy. The actual engine starts off as the same N55 3.0-litre six thatâ€™s used in regular 3 Series and 4 Series cars, but it comes with two 10 per cent larger turbochargers, a 20 per cent more efficient liquid-cooling system, a 35 per cent bigger oil cooler, and a crank thatâ€™s both forged and lighter than the standard item.
Alpina B4 S Biturbo
Engine: 3.0-litre, six-cylinder, biturbo, petrol
Torque: 486lb ft
Gearbox: 8-spd automatic
Top speed: 190mph
Fuel economy: 35.8mpg
CO2 rating: 180g/km
As a result of all that, the Alpina generates a new power peak of 434bhp at 5500-6250rpm and 487lb ft of torque at 3000rpm. Thatâ€™s 9bhp and 81lb ft up on the M4. Unfortunately the eight-speed-auto-only Alpina is 90kg heavier than the automatic BMW, but the B4 Sâ€™s extra torque makes it 0.1 seconds quicker over the 0 to 62mph run at 4.2 seconds.
The suspension settings are carried over from the old B4, which means theyâ€™re still slightly softer than the M4â€™s. Also retained is the BMW Professional infotainment system, adding a widescreen sat-nav and all-round parking sensors. Dakota leather is a no-cost feature, with the Merino leather of the test car weâ€™re driving here a Â£1285 option.
Fire up an M4 and youâ€™ll be greeted by a guttural growl. The B4 S has a more subtle tone through its AkrapoviÄ exhaust. You don’t get much indication of the performance potential in the default Comfort mode, but itâ€™s hard not to be impressed by the effortlessness with which this 1690kg car moves up the road, even with the â€˜box changing up at 2000rpm in normal city driving. Itâ€™ll use all eight gears too.
Put it into Sport mode however and the Alpina mods become more obvious. To the low-down response you can add a prominent and silky-sounding kick-on at 3000rpm and a burly boost forward on each change-up. The Alpina beats the M4 in how it puts its power down to the ground, too, with a more useable elasticity to its delivery compared to the M4â€™s more abrupt, traction-challenging style. That makes the B4 S a friendlier companion when exiting corners under power.
Having said that, the M4â€™s crouching stance and weight advantage do allow it to turn and stop more effectively, but the Alpinaâ€™s softer approach gives it an advantage when road creases and cracks need to be absorbed, even on its big 20-inch Alpina Classic alloys. That compliance, plus superbly weighted steering and a super-responsive gearbox (with a manual shift option via buttons on the wheel) makes it a lot easier to set a quick B-road pace in the Alpina without the will-it-wonâ€™t-it uncertainty of the M4Â on slippery surfaces.
Itâ€™s an easy and rewarding drive that you can dial back to Comfort for even easier wafting if the fancy takes you. Some would call the B4 S less focused than the M4: others would call it more flexible.
The only complaint, and itâ€™s a relative one, is the absence of high-tech infotainment. Although the BMW system has a classic simplicity about it with analogue dials that nicely fit its character, it’s nowhere near as theatrically impressive as the Audi RS5â€™s Virtual Cockpit.
As BMWâ€™s M products seem to be increasingly heading down a slightly more â€˜in your faceâ€™ route, theÂ Alpina is a refreshing taste of subtlety in the performance coupÃ© field. For ultimate hard-edged sharpness, one of the other cars mentioned here will be the answer, but if youâ€™re happy to have a side order of relaxation along with your main meal, the B4 S is an extremely attractive choice. Not to mention a very rare one.