You're comparing two products with the same value prop: transporting people and goods more effectively than carrying/walking.
In terms of mining, a drilling machine is more effective than a pickaxe. But we're comparing current drilling machines to potential drilling machines, so the actual comparison would be:
is an AI-designed drilling machine likely to be more productive (for any given definition of productivity) than a human-designed one?
Well, we know from experience that when (loosely defined) "AI" is used in, for e.g. pharma research, it reaps some benefits - but does not replace wholesale the drug approval process and its still a tool used by - as I originally said - human beings that impose strict parameters on both input and output as part of a larger product and method.
Back to your example: could a series of algorithmic steps - without any human intervention - provide a better car than any modern car designers? As it stands, no, nor is it on the horizon. Can it be used to spin through 4 million slight variations in hood ornaments and return the top 250 in terms of wind resistance? Maybe, and only if a human operator sets up the experiment correctly.