Why are cars getting bigger? A theory.

Another interesting contributing factor are safety regulations and their knock-on effects, which weren't immediately obvious when they were implemented.

For instance, in an effort to reduce pedestrian fatalities from frontal collisions, vehicles in the US were mandated to have at least three inches of crumple space between the hood of the car and the engine block. The thinking being that more crumple depth would help prevent fatalities and serious injuries that occurred when a pedestrian hit the hood of the vehicle, which would deflect, allowing those soft human bits to continue right into the (not soft at all) engine block.

Well increasing the height of the hood of the vehicle meant that they had to raise the A-pillar, which raised the height of the window opening on the doors, since the bottom of the side windows generally lines up with the hood on passenger vehicles. This meant that the side body panels of the vehicle just generally increased in size, and in an effort to maintain a proportional look, the wheels also had to increase in size otherwise they would look weirdly small. And to maintain a comparable amount of visibility out the windshield and side windows, the roof of the vehicle had to be raised to compensate for the new position of the window sill in the doors.

So something that was intended to just add an inch or two of height to the hoods of existing passenger vehicles to satisfy a safety need, ended scaling up the entire vehicle.

It’s also (western) safety standards. Even small cars are larger; compare an 80s Corolla to a 90s to a 2010s. Compare bmw 3-series across the same time span. To make cars safer for occupants, you need more metal and more space. So they got larger.