creating a vehicle with efficiency and gas mileage

You can buy camp cooking stoves that run on unleaded etc and work by turning the fuel into a vapour via the heat of the flame

this is only the small single burner style but its the easiest to see how it works

www.colemanaustralia.com.au...™-sportster™-ii-stove.aspx

so its a similar principle to the op's car idea