Hybrid car hire could be good. Try and develop it perhaps or even try and sell it on to one of the big car rental companies.
Budgetcars.net isn't the greatest but you could always try to develop a site but you are limited with what you can do to be honest imho
No problem.
But make sure you do something quite soon as fuel prices look to be heading down again. I've noticed this at many petrol stations yesterday.
Good luck