£4k! sod that. I got a saxo vtr at 18, then bought a civic type r at 20 and now have a R32 at 22. Never paid more than £1500 (CTR) for insurance. Saxo was £1000 a year and was a great fun car, looking back was not worth that much though, even though it was quick for my age.
Going off that i should be looking at RS4/M3 at 24

Just wait, maybe look at mk4 gti's for now, they wont drop much more in value so will be good untill you 20?