Safety regulations are keeping our MPGs down. They're requiring the use of heavier and heavier steels to turn our cars into rolling padded-wall asylum cells.
Emissions regulations are keeping our MPGs down. Our fixation with NOx emissions and lower HC and CO limits with every passing year prevents our engines from operating at peak efficiency, as motors burn excessively rich to keep the catalytic converters warm.
It also doesn't help that cars these days are getting bigger and bigger, and ever more garish wheels. 22" wheels and up, no limit! Bigger wheels have a very detrimental effect on gas mileage, as they increase unsprung weight by a great deal.
And finally, cars these days are obscenely powerful. Family sedans with 300 horsepower where they only had 200 a decade ago are keeping up with advances in engine design to maximize power, but not fuel efficiency. Instead of 3.5, 3.7 and 4 liter naturally aspirated V6 motors, they could have kept power at the 200hp threshold but instead installed turbocharged four-cylinder motors.
All of that being said, compare a 2004-up Prius to the high-MPG econoboxes of years past, and the Prius feels like a Rolls-Royce, all the while getting amazing gas mileage. I took one through a 2.5 mile urban loop and pulled 150mpg in a friendly competition a couple of years ago - and I didn't even get the best mileage!
One of my friends just got a 2004 Prius for $6500. With their price coming down to this level, anyone can afford them and have a modern, safe, reliable, and highly fuel-efficient vehicle. Living in Southern California, I may buy one for myself in a couple of years.
