Cheers chaps, I thought the blog would be a good record of what I've done, when I've done it and what it acheived The advantage of simulating on the rollers is that a) you get to boot it in a controlled environment, so no other road users it's monitored at all times and you can concentrate on what the car is doing not the road c) after a mapping session it needs a simulation to check how the car runs on the new map under normal driving conditions and load