Board Thread:Game Discussion/@comment-28141686-20160609144035/@comment-26388545-20160609165617

Yup. Once you upgrade then restore you can't race again until the challenge is over. Every time you do, it will overwrite your top speed with whatever you just ran.

Same on every challenge. Some people used to max their car to get more overtakes per race, or get distance faster, then restore. Do that now and race that car again... your numbers will disappear fast.

It evens the playing field a bit.