I was a very lucky boy yesterday, because I got to drive a BMW M635 CSi. This was, and still is, one of the best sports cars ever built. I know we're all supposed to get emotional about Porsche 911s as everyday performance cars, but they’re so damned common these days, and not nearly as comfy. The 635 was a proper continent-crusher that would gobble autoroute, autostrada and autobahn with casual abandon.

Sadly, I didn't get to do any gobbling yesterday. The driving conditions were hardly ideal: a monsoon in central London, combined with a traffic-jammed Hyde Park Corner and a South Kensington High Street that was similarly teaming, meant I didn't get to sample the BMW's on-limit handling, either.

Still, I was in highly familiar territory. I used to sell brand new 6s and these were routes on which I used to demonstrate what an all-round sexy beast it was. I remember one customer I passengered with had a bit of a deathwish; she closed in on terminal velocity on The Mall, and nearly gate-crashed Her Majesty’s tea party. Luckily the car stood up to the abuse better than I did; I had to extract myself from the footwell quite carefully.

Twenty-one years after it was built, this car still felt taut, lithe and very compact. You could see every corner of it clearly and so, despite the fact that tipper lorries and buses were doing their best to drive over me, I could always see precisely what was going on.

The best thing about these older cars is that you don’t feel detached from the driving experience. No need for i-Drive here, although there was a neat computer that I could tap at. I found that I still knew how to set up the immobiliser function, too; not that it was the cleverest thing to do when the lights turned green in Knightsbridge.

So it’s great to drive in a traffic jam, but it’s also sensational to look at. Sharp, aggressive and such a rare sight. What's more, I can buy a standard issue BMW 635 CSi (probably a rusty one, mind) for under £2000; I’m currently sorely tempted.

The 1986, 65,000-mile, fashionably white M635 CSi I test drove, however, was at a dealer, and up for £16,995. Not such a bargain, I'll admit; but it would be a proper way to treat myself.