25% is higher than I thought, although that is number of parts I assume rather than value? Eg a single USA part is the battery, which I would guess is worth more than all the Mexican supplied parts combined.
The bigger risk is to the overall US economy. It could be worse than 5%:
"The statement warned further that if Mexico did not act as Trump demanded, tariffs would go up to 10% by July, 15% by August, 20% by September and reach a permanent level of 25% by October."