As far as LPG servicing goes we can cover all sorts of miles, if the customer literaly says its completely fine then a quick drive up the road and back with the laptop is enough, if there is any known faults or ones that show then I could easily cover 30 miles whilst checking the map or looking at engine diagnostics.

Obviously when we do a conversion we can put a fair few miles on cars, some customers hate it others don't care, they are pre warned that this may be the case though.

One car I did probably do upto 80 + miles in though was a Merc S420 iirc, it had been in several times with a cutting out on lpg fault, it would seem that no matter how you drove it I'd never experience the fault until one day I just drove at a constant speed for 30 odd miles on the A1 and found that the water temp was dropping off thus causing it to flick back to petrol.

A small roadtest would NEVER of shown that up and tbh it had been in several times before I managed to diagnose it with that fault so you could say I took the piss clocking up so many miles but sometimes it HAS to be done