Thread:ME7/@comment-223.176.189.116-20180103065911/@comment-28169398-20180105023441

There are numerous posts about this on the Game Forum. Look there.

Also, if you look up at the top there is a menu that says Navigation. Hover over that and you see Strategy. Hover over that and you will see Upgrade Guide (Subjective), which links to RR3 Wiki:Upgrades Strategy For 100% Completion.

On RR3 Wiki:Upgrades Strategy For 100% Completion you can go to Legend and find Endurance Kings. spending 258 on the Porsche should let you complete the series if you also have the other two cars to run their showcases.

If you click through to Endurance Kings, you will see this sentence in the introduction. "All tiers and 89% completion can be reached without upgrades." That means you can run the 10 - Lap race with R$ only upgrades.

If you are saying that you cannot reach the Final tier, then that means that it is necessary to either upgrade one of the two cars you have with gold or you need the Porsche, which can be won very easily in Road To Le Mans to get the trophies from its Showcase.