Ivan brought an interesting issue on hand, and i decided to investigate. Here it is (all measurements taken in gramms):
Front fenders: 150 each
Door panels: 140 each
Rear quarters: 200 each
Front clip: 300
Rear clip: 180
Rocker panels: 150 both
C pillar covers: 80 both
Hood: 210
Trunk: 180
Front suspension: 180
Rear suspension+diff: 360
Gearbox and driveshaft: 190
Door mechanism: 180 both
Engine: 480
Tires: 140 each
Body shell: 1850
-----------------------------
Makes
Outer panels: 2080
Chassis with drivetrain: 3800
Together: 5880

So, now that i know where the weght is, i can tweak it more sensibly. It is obvious that just about every component, except the tires, will become lighter.