On Thu, 28 Nov 2013 15:15:01 +0000, The Natural Philosopher wrote:

really what planet do you live on that has zero G ?, next thing you'll
be telling me is that the number of passangers doesn't affect mpg.

Just for our enlightenment, how do passengers influence performance on
a rolling road?

tyre rolling resistance for one.

I would be extremely surprised if the rolling road didn't compensate for
measured mass.