It was longer than 40 years. Gas was cheap enough that nobody cared 'til the early '70s when they had to wait in lines for gas, then crappy little poopboxes became all the rage. That's also when you got the EPA and the Feds began mandating mileage requirements.It's crazy to think that 30-40 years ago, the majority of mankind didn't know what their vehicle's mpg even was, and could care less if they did know lol.
It moves in cycles as the price of oil goes up and down. When it's down, nobody cares that they're driving a gas guzzler, but when it goes up, people flip smooth out and start shopping for econoboxes.