Tax Rates (1 Jan 2011 to 31 July 2012): HMRC
(N.B. This URL changes frequently, probably to intentionally make it difficult to find. Last time we found it by searching for "Hydrocarbon Oils", which is of course the first thing anyone would think of. Even when you find it, you can't figure how how you have got to it other than by searching!)
The above are just taxes on fuel — don't forget there are a plethora of other stealth taxes imposed upon drivers: