This is a UK-only thing I think, it's a measure of "insurance risk" and goes all the way up to 20. You can run a search here

http://www.abi.org.uk/carinsurance/

I called Mazda UK today and they say they say they still don't know what group the RX-8 is going to be in, but the Audi TT for example is in group 17/18 depending on model, along with most of the sportier models in the BMW 3 series. The M3 is in group 20.

The MX-5 (Miata) is way down there in group 13, which cuts my insurance costs quite a bit. The most recent model of the RX-7 is in group 20.

 

Group 20 isnt a 'real' group as in the rest of them, just a category which holds special (re: expensive) cases.

I'm assuming this car will be 17-18ish. Similar to the AudiTT as it has close performance, purchace price (ok its a bit cheaper than a tt) etc. It may get bumperd up/down depending on repair costs, security featurs etc.

 

Yeah, it's where they put any cars that are off-scale-high in terms of risk. I imagine such cars are treated very carefully on a case by case basis; I know there are specialist insurers who only deal with such cars.

It doesn't necessarily mean expensive, just high-risk, e.g. you'll see some relatively cheap but very nickable cars like top whack Evos and Imprezas in group 20, but a 70k *diesel* Mercedes might languish down in group 17/18 because no joyrider in his right mind would take it.