It is hardly a joyful state of affairs, but the end is in sight for BMW’s current M5.As production of BMW’s last naturally aspirated M5 peters out, there is a small window of opportunity for agile marketers.Anybody with a compelling F10 alternative (quicker than the new 550i) can gain some market traction before the fifth generation M5 debuts next year.Naturally, Alpina is at the ready with its interpretation of what a contemporary 5 Series performance sedan should constitute. The thinking man's F10 M5?Teases in concept sketches, the Alpina B5 was finally unveiled for public inspection in the glorious sunshine which blessed the Goodwood Festival of Speed recently.Aesthetically the B5 is a classic Alpina design – subtle, yet stylish. The car’s front and rear F10 specification bumpers are replaced with shapelier Alpina units, whilst an aft diffuser/spoiler combination headlines as the key airflow management add-on. Fleshing out the B5’s styling upgrades are a set of classic multi-spoke, turbine design Alpina alloy wheels measuring 20-inches across and rolling Michelin Pilot Super Sport tires - measuring 255/35 up front and 285/30 aft. Aplina's take on the F10’s cabin architecture sees new leather upholstery, adjustable sport seats, a Lavalina steering wheel, Alpina road- and engine-speed dials and classic myrtle wood trim adding the requisite texture contrast.Beyond the subtle styling and trim upgrades this B5 offering’s suite of mechanical upgrades are characteristic of the Alpina brand.The Bucloe-based concern has been racing BMW products for nearly four decades and has enjoyed German TUF recognition as a manufacturer since 1983. In this time Alpina’s built its reputation around a portfolio of tasteful styling and trim upgrades, backed by impeccably engineered technical modifications. Neat power boostCourtesy of custom-made Honeywell-Garrett turbochargers, the 4.4l direct-injection BMW V8 powering the B5 tallies peak outputs of 378kW and 700Nm. Each of the two turbochargers comprising the Bi-Turbo configuration feeds an individual bank of four cylindersBMW’s reverse-port flow 4.4l bi-turbo V8’s 58kW power gain in B5 trim (up from 300kW) is impressive, yet remains well shy of the M-division SUVs output of 408kW and BMW’s predicted M5 peak power figure of 425kW. M5 humbling pace is not the B5’s raison d'être though – although Alpina claims it is good for dispatching the benchmark 0-100km/h in 4.7 sec before powering on to a top speed of 307km/h. Alpina’s marketing rationale is to offer something approaching (not eclipsing) M5 levels of performance with a rewarding, instead of challenging, driving experience. To this end Alpina’s partnered with ZF, who designed and manufacture the new eight-speed automatic transmission driving BMW’s F10 5 Series cars.Channelling the B5’s power to the rear wheels is a specially adapted version of the new eight-speed automatic transmission which features a more urgent shift regime intended to optimise the increased engine output when required. As opposed to the BMW E60 M5’s rather unforgiving sequential manual transmission, the B5’s eight-speed automatic effortlessly defaults into unobtrusive operation when motoring around trafficked urban environments. Dynamic harmony was a key design directive for Alpina’s engineers tasked with B5 project. Ensuring sufficient braking power are larger ventilated rotors front and rear, measuring 373- and 370mm. To shore up the F10’s already outstanding ride and handling characteristics ever further Alpina has recalibrated the car's adaptive dampers in B5 trim to provide more camber at the front wheels.So, if you simply cannot for BMW's F10 M5 (due early next year) this Alpina B5 is a very fetching alternative.