A smart car would be equivalent to something smaller, like a 3-3.5" screen. The car equivalent of the 4-4.3" screen would be something like a Mini Cooper, a miata, or even a 3 series, where the larger 5" screens would be comparable to bigger sedans like the dodge charger, ford Taurus, or BMW 7 series.
The nexus 7 was never high end, it was meant to compete with the low end kindle fire. “high end” specs (arguable), maybe. But it was never marketed as a high end device. Just a cheap tablet with decent specs. The various build quality issues it had are a testament to that.