If like me, you've just read the other guides posted here and realised that you have spent most your winnings and do not have the requested parts. There may yet be hope. You can't get anymore money from races btw, but you wont need it.
Firstly the chievo should read have all the best upgrades installed. This is important.
Next Junk yard is your friend here. Learn what the items are below and be able to spot them easily;
Traction - R-600 Repulsorgrip
Turning - Control Stabilizer
Accelerate - MAG-6 Injector
Top Speed - Block6 Thrust Coil
Air Brake - Quadrijet Air Brake
Cooling - Turbo Coolant Pump
Repair - Cluster2 Power Plug
To reset the junkyard you can race, or as I did, back out to the title screen then go straight back into you save file and go for the first race that appears, but we wont be racing just heading for the pre-race Junk Yard option
Next look for one for these 'best upgrade' items in the Junkyard, if it is one you already own like a Block6 Thrust Coil for example. See if the trade purchase value is in minus ie -2390. If so buy it, banking the extra cash. There are little green vertical bars that show an items quality. Keep doing this so that the quality of your 'Best Upgrades' diminish but regardless you have them installed on your racer
When you spot an item on the list that you need and you can afford it, buy it. After 5-10 minutes of reducing the quality of my gear, banking the money difference and looking for parts I needed, I finally had enough to just buy the last part from the actual shop.
Hope this works for anyone at the end wondering if they need to play again.