what happens if no heat left but wanna go from gear 2 to gear 4?

[Gemmi_from_Freiburg]

what happens if no heat left but wanna go from gear 2 to gear 4?

Last game I crossed the finishes line with 3 cards but wanted to play 4. I thought I might crash so only played 3 cards because I had no heat card left to discard. Now I wish I would have tried what would have happend. I couldn´t find anything about this case in the rules. Does anybody have any idea?

[thoun]

You just can't

[witherx8]

I’ve just got this and the game won’t let me play

[kirin0205]

You can't. You need to have a heat to go from 2 to 4