Today i have been to the Jap car show at Billing and there was a Dynopack running giving out BHP figures.

Basically you unbolt your wheels and bolt on a special set of hub fittings, they go into the Dynopack and the car is run up giving a BHP figure AT THE WHEELS.
The machine is totally Digital and i think rolling roads are anologue so i would of thought these would be better

Take a look at the web site and click on Dynopack

http://www.thor-racing.co.uk/