Top Speed Failed!


So I was trying to turn the mazda mx5 mk1 to a drift car I’ve upgraded almost everything to race specs and swamp it with a v8 just to check it !

When I tried to tune it tho the Tops speed and breaking speed wasn’t showing instead it said Failed to both of them ! At the beginning it was funny
I thought I just gave birth to a DK but then I found it a bit hard when I was trying to mess with gears ! I don’t know if that happens to other cars to but it’s surely does on the mk1

So is there a way to fix it ? Is it any type of bug or I probably made anything wrong with the tuning ?