It ain't perfect
But for a city car... Yeah, don't see the issue:
https://www.adac.de/rund-ums-fahrzeug/autokatalog/crashtest/details/474/smart-fortwo/
It's the same way a guy I went on a few dates with once (he was paramedic) swore that old Audi A6's were the safest cars cause he never pulled a dead body from one.
If you have an opinion, it's just that, an opinion.
Yeah, physics don't change. Engineering does though.
There is a very specific reason why it isn't uncommon to total newer cars even in collisions as low as 50kMh / 30MPH inner city nowadays.
The frames of modern cars are specifically designed to compress in certain areas and not others under very specific loads.
Everything about a car now is exactly calculated to spread energy dissipation throughout structures so that your body only experiences prespecified loads.
If your car is totalled, but you walk away unharmed, I think the value proposition of that is obvious.
I certainly feel perfectly safe in Polo, even on the highway.
Fuel efficiency. Yeah the Smart wasn't terribly efficient that is true.
My Polo gets something like 40MPG in daily driving.
My mum gets about the same in her Fabia - which has the newer revision of basically the same motor.
At some point, you won't get much more efficient regardless of size.