I was 21 when I passed my test and bought my first car. Decided I didn't really want to start at the bottom rung e.g. a 1.2 Fiesta, so I went with an '02 1.6 Astra instead. Got a lot more car for my money than I would have on the equivalent Fiesta, Clio etc, insurance was horrendous for the first year (just shy of two grand), second year was nearly half but still expensive and it came down significantly after that.
Still got it nearly five years later though so the way I see it, I've saved money in the long run because I haven't really felt the need to change cars. It's still quick enough for me and will go when you want it to (as much as a 1.6 can 'go', that is), and the extra size over a smaller hatchback has been useful when I've moved house etc. Always worth thinking ahead.