Mine varies a lot between the cars. The Caterham 7 is £180 a year. The 370Z is £300 a year, but the F82 M4 is £1100 a year, and the GLE400d is £1300 a year.
The Caterham and 370Z basically stay the same every year, whereas the M4 and GLE go up £200 every year in comparison. Bloody German cars!
I do wonder if a multi car policy would be a better bet, but I've heard that multi car policies are great for the first year, but then they shoot up loads after that though.