My GTR at Clive Atthowe

[duncan]

The slight increase in wheel bhp is down to the reduced loss of power through the transmission as the gearbox oil and diffs warm up.

Absolutely - the Dastek rollers measure the coast down losses for each run to add these to the wheels figures to give the flywheel figures.

[Richf]

warm tyres can stick to rollers increasing drag and therefore drivetrain losses

[Fast Eddy]

I thought it was something like that to give different losses per run in effect