there's not a meaningful way to pick the "best" in that group that everyone will agree on
Metrics often don't provide a definitive answer about what the best thing is, with universal agreement. If I tell you Apple scores highest in customer satisfaction for smartphones last year, does that mean everyone will agree that the iPhone is the best phone? If a bunch of people are working at a helpdesk, and one closes the most tickets per hour, does that necessarily mean that he's the best helpdesk tech?
It's true that a lot of people misuse metrics, thinking that they always provide an easy answer, without understanding what they actually mean. That doesn't mean that metrics are useless.
If you're comparing a bunch of cars that get 32-35 mpg and go 130-140 mph, there's not a meaningful way to pick the "best" in that group that everyone will agree on
Yeah, but that's a really dumb metric since most people don't actually care what the top speed of a car is. Or to be more truthful, only morons care about top speed unless it's below 80mph, since you basically shouldn't be driving your car that fast. So really, in a metric like this, the "top speed" isn't a metric of "faster is better". It's a metric of "fast enough is good enough".
But if you were in the habit of doing car reviews, it might make sense to take a bunch of assessments, qualitative and quantitative, like acceleration and handling, MPG, physical attractiveness, additional features, and price (lower is better), and then weigh and average each score. That would enable you to come up with a final score which, while subjective, makes some attempt to enable an overall ranking of the cars. In fact, this is the sort of thing that reviewers sometimes do.