I was driving Autocar’s long-term Mazda CX-7 the other day and noticed that it had an unusual design feature: the doors wrap right around the sills. It’s a design feature that’s all too often overlooked.

In 1999 I attended the launch of the Audi (A6) Allroad, which took place in the Austrian Alps.

(It’s a launch that sticks in my mind partly because the episode of Eastenders running on the BBC World channel that day had English subtitles).

We had to drive the Audi up a pretty challenging, muddy, track to the peal of the mountain and then down the other side. The Allroad was impressively agile and capable, mostly because it was one of the first ‘soft-roaders’ with proper, permanent, four-wheel drive.

However, as we clambered out of the test cars, we all experienced the same design flaw. The mud on the Allroad’s extended sills was promptly transferred to the back of our left leg of our trousers.

The Audi bosses laughed and said the same thing had happened to them. Hilarious, I thought.

Proper off-roaders have doors that wrap over the sill to prevent the problem, as did the original Saab 900, a road car designed for slush-bound Scandinavia. Indeed Audi used to fit thick rubber strips to the lower doors of its cars (my old 90 20V Quattro sport had them) to keep the sills clean.