I've been away from PC for a year or so--I sold my 3rd Gen Prius as part of a move west. Now I'm looking for a new car. More of the story in another post, but here I have one question: How do Toyota and other manufacturers get significantly different MPGs from the same basic hybrid/body combination. I see, for example that the 2019 Camry Hybrid is about 52 MPG in the LE version, but only 47 in higher trim. A competitor that I'm looking at, Hyundai Ionic Hybrid is about 57 in the base version, 55 in the higher trim. Prius Gen 4--56 in Eco; 52 in other trim. How do they do that? Are the drivetrains tuned differently or different computer programs? Is it all weight? I'm having a bit of trouble figuring it out.
I'm going to assume they are using the same drive trains, since truly different federal and CARB engines are no longer the norm. You can check by comparing the engine codes on Fueleconomy.gov, it's reported under the smog rating. So it is mostly weight, but some of the weight effects may have more bearing on the test parameters. Getting the car to fall into a lighter weight category could mean easier settings on the test equipment. Then depending on were the weight is can have a bigger impact. In those examples, the less efficient version has bigger, heavier wheels and tires. That is the worse place to add weight for efficiency. The Canadian Camry hybrid LE has the same wheels as the ICE version, but otherwise the same as the US spec one with smaller steel wheels, and its rating is lower.
Mostly weight (so they can be classified in a different EPA weighting bracket) For the Prius Eco (or now called L Eco for 2020) Lightest version of the Prius Uses the Li-Ion battery No rear wiper for aerodynamics IR Heat-Reflective windshield Factory tire pressures pumped up higher than regular versions (39/36 PSI vs. 36/35 PSI on regular Prii) No spare tire to save weight For the Camry Hybrid LE has 16" steel wheels w/ full wheel covers vs. the SE/XLE's 18" alloys (weight savings plus less rolling resistance right there) Li-Ion on the LE, NiMH on the SE/XLE The LE obviously weighs less than the SE/XLE with less equipment (no moonroof, leather, no embedded nav or power passenger seat etc) You can see the difference in mpg between the US spec Camry LE Hybrid and the Canadian spec LE Hybrid as the Canadian spec comes with 17" alloys as standard and drops to 48mpg. Edit: Here's the thread 2018 Camry MPG Table | PriusChat
Mostly weight difference as already mentioned. Also higher trims sometimes have larger wheels and tires for the "look" making it bit less efficient.