[Savage GT]

Hers my pairing:

   

One arrived with a wobbly front wheel, the other had a wobbly rear.
I know full well the problems I have with Scalextric cars, but still sometimes I can't resist the pretty 

Lots of work and aftermarket parts to make them barely decent runners, are they better than they were? Yes.
Was it worth the cost and time spent to make it so? Not in my opinion.

You can remove most of the Scalextric, but it's still a Scalextric!

List of things changed:

Axle for Pioneer one. (No room for grub screw fiitting gears, so using Pioneer means I have a gear fitted on a knurled section on the axle and I can at least fit set screw wheels onto them).
Rear bushes 1mm offset to reduce the huge gap between chassis and track.
Slot.it front tyres (smaller diameter to help with the above).
Sloting Plus front axle.
Jmay (of this forum) Wood track guide for Scalextric cars.
Wasp Urethane rear tyres.
Staffs "minilight" wheels.

Some shaving of chassis to allow a small amount of body rock (limited by wanting to keep appearance good, scalextric designing parts of the body on the chassis is another bugbear for me).

The SCX 'Cuda runs far better without any parts or work, pity they still don't produce them !