Have you considdered car hire?
When I looked into it, the cost of insurance+tax+mot+breakdowns(+service if you cant DIY it) meant it was cheeper to hire a car almost every weekend for a year than it was to buy and run one. But thats me at 23, might be different at 17.
Even now at 24 with a very good income, probaly less than 15% of my peer group at work have cars, and thats excluding the ones who live in london who don't have a car because it would be a waste of time. No one can justify the premiums (say £800) depreciation (say £1k on a £5k stra) and garage bills (£200 expected + £???? if it breaks down), and despite the wingeing, trains are still about as expensive as petrol so for traveling alone/infrequently make sense.
I've just resigned myself to not bothering with a real car untill I'm in my late 20's and/or commuting by bike is no longer an option.