[autoavia]

The most likely source for these parts would be Ebay as some sellers break cars and sell off the bits but sometimes you can find a complete but battered car that still has the bits you want which is cheaper than buying the spare parts.

 Did a quick search and found these but they aren't that cheap

http://www.scalextric-car.co.uk/Parts/Bu...t_XR3i.htm

http://www.scalextric-car.co.uk/Parts/Wi...tus_72.htm

An alternative for the Quattro could be a 3D printed chassis from Amato chassis design

This is the link to the PDF for his chassis list on Slotforum. Just click on the link for the PDF and it will download.

https://www.slotforum.com/forums/index.p...pic=195743 

His chassis work very well and are usually pretty easy to fit and should handle better than the original so the car will be faster.