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PT Cruiser

Why does a Honda Accord get better mpg

than a smaller PT Cruiser?

The PT cruiser isn’t very aerodynamic.

In addition, there are probably thousands of small technical differences between the two cars that could also account for the difference in fuel economy. I would not know where to begin.

You could also compare the weights of the two vehicles.

The PT Cruiser is heavier, less aerodynamic, and has less fuel efficent engineering and technology than a Honda Accord. Honda works hard to claims of high mpg by using costlier lighter weight materials, better engine fuel management, and slipperier shapes to achieve high mpg. American mfg’ers were paying more attention to performance (the 0 to 60 kind) and creature comforts like cupholders.

The PT Cruiser is a pretty good little package however. Decent mpg without a turbo, good carrying capacity, flexible seating and cargo setups, and attractive price. The high mpg with Honda comes with a high Honda price tag.

While larger heavier cars do tend to get lower mileage than small cars, there are other factors including the efficiency of the engine, aerodynamics, even tyres and fuel used.

Honda builds some of the most efficient engines around. They really work hard on getting the most out of their motors. That, plus the aerodynamics of the Accord are probably much better than the PT Cruiser.

When they styled the PT Cruiser to look like a car from the '40s they also partly took its aerodynamics back to the '40s.

First off, the PT Cruiser isn’t smaller than the Accord in the dimensions that matter.
Thats akin to asking why a pickup truck, or a city bus doesn’t get better gas mileage than an Accord.

If you sit the 2 cars next to each other, you should start seeing the differences immediately. The PT Cruiser is considerably taller than the Accord. 63" tall vs 58" tall. The drag coefficient of the PT Cruiser is .39, while the Accord is right around .30. To give you an idea, another vehicle with a .39 cd is a Chevrolet Tahoe, or a Dodge Durango. My Porsche Boxster has a cd of .29, for comparison.

Minimizing drag is done to improve fuel efficiency at highway speeds, where aerodynamic effects represent a substantial fraction of the energy needed to keep the car moving.

About 60% of the power required to cruise at highway speeds is taken up overcoming air drag, and this increases very quickly at high speed. Therefore, a vehicle with substantially better aerodynamics will be much more fuel efficient.

Then there are things that you can’t see, like the transmission gearing.
Chances are the overall gearing in top gear of the Accord allows the engine to rev lower at highway speeds than the PT Cruiser.