oh wow - so lemme see a quick equation. If GTA3 had x landmass and 40 cars and 10 weapons and no motorbikes - and I racked up 284 hours of gametime (that's right, I've spent almost two weeks inside that game) and GTA - Vice City has 2x landmass and 120 cars and 40 weapons and motorbikes then:

if GTA3 = x(40+10+0) = 284
then x = 5.68.
therefore
GTA(VC) = 2x(120+40+1) = 1828 hours of gametime.
this is equivalent to 45 working weeks - well nigh a full working year. I think I need to go and lie down.