Question : Theoretical Laptime

Here is one for the stats nuts among us.

I am trying to work out a way to find a theoretical laptime at a go karting event I am running.
A great lap is 40.5 seconds but the heavier drivers clearly get penalised. It is estimated that 10kgs of weight means approximatley 0.3 seconds a lap slower. The karts weigh about 110kgs.

I know all the weights of the drivers and their fastest laps.

All ideas are welcome.

(Sorry, didn't mean to add the wireless zone)

Answer : Theoretical Laptime

the simplest regression meyhod is probably least squares
http://mathworld.wolfram.com/LeastSquaresFitting.html