I refer the hon. Gentleman to the answer I gave the hon. Member for Stroud (Mr. Drew) on 12 November 2007 and the hon. Member for Colchester (Bob Russell) on 28 April 2008.
HMRC allows volunteers to use the approved mileage allowance payment (AMAP) rate for convenience, but it is not mandatory and volunteer drivers can claim tax relief for the full cost of motoring by completing a return, if they wish to do so.