Theoretically...

[Stonedofmoo]

So if you could run on tyres as thin as cheese wire, gravity and therefore friction wouldnt have much impact either?

 

[saitrix]

So if you could run on tyres as thin as cheese wire, gravity and therefore friction wouldnt have much impact either?

Yup. Smaller the contact patch, the less friction you have. Ever wonders why in the tour de France they have such thin tyres? Thats why.

 

[volospian]

How much of a factor would gravity be though assuming the ground was perfectly level the whole distance

I don't know the physical equasions of it, but as gravity would increase fricton as it tries to press the car into the ground, I'm assuming that the 1bhp car, unless it was incrediblyy light, would be severely hindered by any gravity at all.

Remember the gravity would press the tyres to the floor and the bearings along each connection (crank, gearbox, driveshaft, diff, hubs, etc.) and every such joint would create a loss in power

/edit, sorry was slow to post and saitrix beat me to it, with equations and all!!