my mk3 16v does about 25mpg round town, but about 38-39 on a run, is fast, wot u expect from a 150bhp car :)i only puched mine to 110mph, but loads more in it.
As for reliability not let me down so far in 2 months that i owned her.
Heard it handle better on uprated suspension, but mine feel ok to me, but thats prob cos i been driving a 1.2 punto for last year lol
And I would personally buy an unmodified model!