After the pioneering M1, the next car to use the mid-engined icon’s 24-valve straight-six was the M635 CSi. It was a fine car, but a few months later there came a more significant, more bespoke and wickedly understated sedan with the same 213kW version of the engine – the first M5. The M5 was hand-built by BMW Motorsport and, in the UK (it wasn’t offered in Australia), it cost most than a Ferrari 308. That it was more powerful and faster went some way to justifying that sticker shock.

Stealth was a key part of the M5’s appeal, cross-spoke BBS alloys and subtle body-coloured arch brows the main clues to its potential. There was little take-up of the optional body kit, which is entirely understandable as the same addenda was fitted as standard to the wannabe M535i.

The original M5 looks petite alongside every M5 from the V10-powered E60 onwards, and the current M3 takes up more real estate. Inside, however, its roomy cockpit feels airy thanks to those tall, thin roof pillars. Fine seats put you at the heart of things, the dash is angled towards the driver and the clarity of the instruments set into it were already BMW hallmarks in 1985.

The straight-six sounds gorgeous, idling with a slow, steady rumble that is somehow full of intent and confidence. The last E28 M5 that I drove had over 225,000km on the clock, so the gearshift was a little loose and the recirculating-ball steering a touch vague about the straight-ahead, yet the engine was silky and pulled low revs and high gears with ease. For decisive overtakes you always needed to have it spinning above 4000rpm, and even then this 200kW-plus engine doesn’t feel dramatically potent.

There is magic here, though. On the right road, the M5 snaps into focus. As you guide it into a turn and all vagueness vanishes, the meatily weighted steering suddenly sharp and precise, the whole chassis tensed up and responsive. There isn’t the massive grip of the modern cars, but the E28 flows beautifully over the tricky terrain and engages you with its poise and adjustability. It’s so well balanced, and it has steering with feel so you can key into what the car is doing. In other areas it’s unexpectedly good; the seats and gearshift are excellent.