HMRC have announced new rates which apply from 1 March 2015: 

Engine size	Petrol	LPG
1400cc or less	11p	8p
1401cc to 2000cc	13p	10p
Over 2000cc	20p	14p

Engine size	Diesel
1600cc or less	9p
1601cc to 2000cc	11p
Over 2000cc	14p

Hybrid cars are treated as either petrol or diesel cars for this purpose.