That's for fuel efficiency reasons. Cars lower to the ground get much better mileage at highway speeds since they have less aerodynamic drag. And it's not just

That's for fuel efficiency reasons. Cars lower to the ground get much better mileage at highway speeds since they have less aerodynamic drag. And it's not just compact cars, modern SUVs, except the ones destined for workhorse off-roading, are also lower to the ground than they were 20 or so years ago since they never leave the city/highway anyway.