DIAL M FOR MORE

Imbued with the magic of BMW Motorsport GmbH, the E24 M635CSi and E28 M5 stand tall as high points for the legendary performance brand 

-  MARTIN BUCKLEY

The E24 M635CSi and E28 T M5-both brawny, built-to-order products of BMW's Motorsport GmbH arm are prime candidates for 'peak BMW' status, in my book anyway. In a world that is becoming ever more sanitised, these cars look, smell and feel like the real deal.

BMW could have come up with a pair of freakish hot rods as a way of promoting the talents of its Motorsport division, but that would not have been its style. On the other hand, to call the M5 and M635CSi subtle tends to underplay their capabilities. Perhaps they are more than just 'peak BMW', but somehow represent the height of achievement in the wider realm of analogue, rear-drive, usable performance cars.

Now fast alighting on their 40th birthdays, neither car was a young design even in the early 1980s. Weight-paring and aerodynamics were not exactly at the top of their designers' priorities, either. But behind those shark-like masks lurks the key to the charm of this M-car duo - and, arguably, something no truly great BMW should be without: a straight-six engine.

From a company that always took more than average pride in even its most humble power units, a semi-productionised version of its Paul Rosche-designed competition 'six' - battle-hardened in the works CSLs since 1974 as the M49- was always going to be special.

With shimmed bucket-tappets and single-row chain-drive for its double overhead camshafts, the 24-valve, 3.5-litre M88/3 was a hand-assembled, civilianised version of the engine found in the mid-engined M1, the car developed by the 180-strong Motorsport division (with a little help from Lamborghini) to take on Porsche in Group 5 racing. The dry-sump M1 had Kugelfischer butterfly-control mechanical fuel injection; in the wet-sumped M635 CSi, the spark plugs, fuel injection and timing were electronically managed by Bosch for an even meatier 286bhp at 6500rpm, along with a more road-friendly torque curve.