Possible but extremely rare, buy the STi yourself as well? With no external funding (ie olds giving you a savings account, money for 18th etc?)
I mean a degree by 20 is rare as it is, you'd have been @ uni since 16-17 and clearly not a dumb kid, so fair enough in that respect and well done if you've been able to achieve it.
Do you still live @ home though? That question was nicely avoided so im guessing yes - which makes all the difference
To the OP - you are talking about what, 80-90k of GTR, that wont appreciate for many years as stated. Fat chance of it going up in the immediate term, and if you intend to buy it and drive it - adding KM's is probably going to cause depreciation. You'd need to hard park it in a bubble realistically.
Smart move is to buy property first.