I have done it in an Iveco jumbo van while on a triumph parts trawl, the diff nearly blew up, and after I vowed to myself to take the PI back and give it a go, what a fabulous bit of road... compares well with the cat and fiddle run in Macclesfield / Buxton where I grew up.... we would need marshalls at the top and bottom though surely? now that my pi is running I may have to take a Sunday drive down there ;) ;