As everyone has said really

Mk4 is heavy and has rubbish handling, but its an effortless drive because of all the electronics and it eats up the motoryway miles. (Dont go for the 2.08v the 1.8T and 1.8 N/A are the pick of the bunch.)
It is easy to tune with a simple remap (190 - 210 bhp depending on engine code) which in a stright line will give you the grin factor, just dont go round any corners

You will have to spend a bit on suspension to get it really usable.
Despite people saying they are unreliable my MK4 has 140K on origanal turbo,MAF, and all four coilpacks!
All depends how its been looked after/ serviced in the past IMO - and Luck of the draw i guess.
Its been a really good car TBH. (Did have a bit of trouble with the water pump...

)
Sure its had a few of the common faults but what car does'nt?
Mk2 is a real drivers car. Great handling loads of fun, still looks great today, you really have to drive it (unlike the MK4) you feel a part of it if that makes sense.
Not many stupid electronics / sensors to go wrong etc Its light because of this too- no airbags in seats etc
They do need to be looked after as any older car does
All MK2's come complete with "The MK2 smell"

All in all MK2 FTW

Or if you can afford it get both - MK2 for fun MK4 for daily
