I am seeing a very similar issue. When in middle of high speed (race or speed challenge, etc..). The acceleration key simply ceases to function. Spamming it has no effect, have to brake and slow vehicle or stop it. Then is starts working again. One time this happened three times during a single race, usually only happens once.
Only controller's connected are mouse and keyboard. PC version Ryzen 7, Radeon 5700 XT.
Add to this that cloud storage saves before the start of race just after taking funds, so you keep having to re-pay entry fee's for the same race. The two issues combined are making it impossible to have an A car for the first Saturday race, and there is no option to restart game from beginning. Basically, am on day 4, still in starter car, no upgrades, and have 0 funds, so can't even enter most of the races on this day.
It would have been helpful if the restart race key had -not- been removed from game. That new restart only at end of race (and limit it) metric has also compounded the problem. So there is no workaround in game anymore for odd issues that easily go past the 10 retries.
So basically, cannot restart game from beginning, and cannot continue.
I have played every NFS from world to this one. I have to say this NFS has been the most disappointing and un-fun version I have seen.
I cannot ask of a refund from Steam because of the time I have put in already, but frankly, the game isn't playable or enjoyable currently. But I would have if I had not exceeded the time limit for that.