Why Hasn’t Fuel Economy Improved in the Last 100 years?

Chances are the car you currently own gets somewhere in the range of 20 to 30 mpg. If you’re on the high end, you might even feel pretty good about that miles per gallon. There’s a problem though – cars back in the 1920s were capable of getting the same miles per gallon. So, what’s the deal? With all the technological innovation in the world, how has the realm of fuel efficiency somehow fallen to the wayside?

To learn more, watch the video below or keep reading! 

In 1923, the average fuel efficiency of cars on the road was 14 mpg. In 1973, the average fuel economy was 11.9 mpg, thanks to the era of land yachts and V-8s. In the 1980s, average mpg was able to jump up into the 20s, but since then, it’s basically stayed there.

Image Source: Concerning Reality

The Model T, which was first produced in 1908, was capable of achieving 30 mpg.

This peculiar problem can be traced to just how technological improvement has affected the automotive industry over the course of the last century.

Most engines have gone from two valves and pushrods to double overhead cams with four valves. Transmission technology has improved drastically with 6, 7, and 8 speeds becoming standard. Computers have allowed for fuel injection to become standard. Tire technology has decreased roll resistance and modern design tools have decreased drag coefficients on car designs.

All of these improvements should be improving fuel economy, right? Well, yes. But there’s something working against them.


Cars are getting heavier and heavier. In 1982, cars weighed on average 3054. By 2006, cars added 500 pounds to 1982’s number and averages are only going up.

The reasoning is twofold: technology and safety is HEAVY, and our buying habits.

All the added technology and safety equipment in modern cars is making them heavier and heavier year by year, meaning that even if engines were to get more efficient, their respective car’s weight would hold them back.

Buying habits are changing too. In 1982, cars made up 80% of the market. By mid-2000s, cars slipped to 48% and trucks and SUVs took the lead for the majority. This trend only continues as we see big brands like Ford eliminating most of their car models in favor of more profitable SUVs and trucks.

The weight gain in this class of vehicles is even worse too. Trucks currently weigh an average of 4712 lb., a 900 lb. increase from 1982.

Cars today are simply bigger and heavier, meaning that overall fuel efficiency is being held back by these other factors. Consumers across the world are shifting to heavier vehicles with faster respective performance.

But, what if modern cars were as light as the cars of the past? Then would they be more efficient?

Image Source: Concerning Reality

The EPA suggests that fuel economy directly varies based on vehicle weight, so yes. If the average car in 2006 dropped its weight down to 1980s numbers, its fuel economy would jump from 24.6 mpg to 28.7 mpg, a 16% improvement.

Conversely, if you kept the same weight and just dialed back the better engine performance, you’d see the same efficiency improvements. If modern cars could shed their increased weight and consumer-desired power, average fuel economy would jump from 24.6 mpg to 33.5 mpg. A staggering improvement.

The final fact of the matter is that the efficiency of modern engines has improved drastically. Stacked head to head, there’s no competition. However, as the modern consumer demands big jacked up trucks and fully loaded SUVs, even these more efficient modern engines can’t deliver on better efficiency compared to last century.
Trevor is a civil engineer (B.S.) by trade and an accomplished writer with a passion for inspiring everyone with new and exciting technologies. He is also a published children’s book author and the producer for the YouTube channel Concerning Reality.

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