You can check the insurance group of any car you might be interested in by starting from this page:
http://www.gocompare....ce/manufacturers.aspx
Take care to check the EXACT model. For example, a 957cc 3 door Fiesta is only in Group 2 but a 1596cc 3 door RS Turbo Fiesta is in Group 15.
It has also been repeatedly mentioned, here on AB, that many young drivers find that they can get a significant discount on their premium by adding an older, more experienced driver (e.g. a parent) onto their policy as a 'named driver'. (Unlike 'fronting', where the older driver is the policy holder with the younger driver as a named driver, doing it the other way round - as I've suggested - is perfectly legal but can sometimes see as much as one third cut from a premium).
Chris