I passed my test at 17 when in 6th form but I didn't get a car until my 20s, when it became pretty necessary due to a new job which involved a 12 mile commute. I'd seen an advert in the local free rag (remember them?) and a dealer was offering a brand new Citroen AX 1.0 for £5,995 with a year's free insurance and 0% finance for one or two years. The offer at the end of the month. So, on Jan 31st - exactly 25 years ago today - I wandered up to the dealer (10 mins walk from home), found a salesman, showed him the advert and said something along the lines of "you've got this offer on which expires today, and I want one". He asked if I'd driven one before, to which I replied no (I'd not driven much at all since passing my test), and he said to hang on and he'd find one to test drive.
A few minutes later, he came back, took me over to a car and told me to take it out. When I got in, he just stood there, so I asked if he was getting in - he replied no, just take it out yourself, so I did for 30 mins or so. When I got back, I told him that I thought he was rather trusting (bearing in mind I'd arrived there on foot and not shown him any id/driving licence!), his response was that he'd been doing this job for something like 20 odd years and he knew an honest customer. Anyway, we did the deal, and 2 days later I picked up a brand new car. It was ideal for my journeys to work, but going down to Birmingham or places for railtours I had to flog it a bit!
When I traded it in (in 2001), I dealt with the same chap who had sold it to me.