I guess you can look at them like houses in the way of over capitalising..
If you buy a house for 100 thou in a street for of 150 thou houses and spend 100thou referbing it, your not going to make it back..
As mentioned before. Their pushing 16-20+ years.
Your nuts if you spend 30k on a gq. Insurance will laugh at you, and so will your mate.
Things like quality bar work, winch, lockers and maybe fresh paint will increase $$$ value.
Lifts, mags, stereo. Waste of time.
How did those GQ's go anyway..?