Features

16:15 The eight LEDs light up through six yellow, two red and then all of them flash simultaneously at max revs. I bang home fourth with a squeeze of the right paddle.

The twin-clutch 'box slams the gear home in a few milliseconds. Fifth, six and seventh flash by, up to around 175mph. It's supposed to be electronically limited to 155mph, but 175mph indicated is about 168/170mph. Roof down, this feels terrifyingly fast.

I lift off and let the car slow to a more manageable speed. I've still got a long way to go. I also don't fancy testing the M3's roll-over system that, like the standard 3-Series convertible, uses sensors in the middle of the car, on the B-pillars and in the doors, to constantly monitor vertical and horizontal movement.

If they detect that the car's going upside-down, roll bars pop up from behind the rear seats, seatbelt pre-tensioners are activated and the head/thorax airbags get deployed.

16:30 I've spent the last 10 minutes wondering if there could be anything more embarrassing than putting somebody else's car into a ditch, a car that I was supposed to be delivering to a photo shoot. The answer, I've decided, is 'no'.

17:00 Being in an open-top car makes you look at the sky. I've started paying a whole lot more attention to clouds. Roof goes up early when I see a bunch of dark ones, and it starts hailing. Cosy and quiet inside.

17:30 The hail has stopped, and the sun's come out. I can't see much with the light reflecting off the spray from big trucks. But there's still that V8 howl...

18:00 I stop at another petrol station to fill up. I'm averaging 18.9mpg. I'm also getting lots of attention from a busload of school kids who take photos. I'm hoping it's the car... and not because its owner looks like he doesn't belong there.

18:15 Odd mesh wind-deflector tested. This thing fits across the back seats with a pop-up section that opens just behind the front headrests. It helps reduce buffeting, and although it isn't elegant, it works well for high-speed touring and can be folded up and stowed away in the boot when you don't want it.