I'm thinking of purchasing a 2020 FIT, but I noticed that the highway mileage rating for the low end LX model is 4 MPG better than the other models (40 vs 36). Since the engine, transmission, and final drive ratio are all the same, what's the reason for the better MPG of the LX model? Is it just the 15" vs 16" wheels?

https://automobiles.honda.com/fit/sp...im-comparison#

 

Smaller wheels, less fake aero, less options.

 

+1 just about to say this.

 

The diameter of the wheels themselves shouldn't make any difference. It is simply the car's height off of the ground that would make a difference. But the larger wheels have smaller tires on them, so the car is very close to the same height off of the ground – I think less than 5 mm difference. What is different about wheels is that the EX models have wheels that weigh less, as well as tires that weigh a bit less. So the EX should have better fuel mileage. But it does not. It is the opposite. Actual reports from the field indicate that LX owners and EX owners get about the same fuel efficiency. The moon roof has very little affect on aerodynamics, and adds maybe 5 kg to the car. The alloy tires probably reduce the weight more than the moon roof inreases the weight. I'm puzzled as to why the EX is rated as being less efficient.

 

interesting. LX going from 6 spd to CVT added 46 lbs, but in the Sport model, going to 6 spd to CVT added 44 lbs. I checked the EX and EXL weight and found that max difference was only 67 and 71 lbs more compared to the LX model. The small difference shouldn't diminish EPA by 2 mpg. So, I suspect it's the wheel and tire size that give the LX model better gas mileage, less air resistance. BTW, earlier Fit, 2017, the rated hp is 130 hp with the CVT, not 128 hp since 2018. Honda must have changed the gearing in the CVT.
I have no regrets buying the 2017 CVT Fit for my daily drive. I get over 40 mpg (calculated) not using the Honda mpg display which used to be off by +2 mpg, but now more accurate with the car nearly 60K miles. The Porsche Turbo was used for 777 miles last year.

 

Weight. Sun roof (80-100 pounds alone) and other factory accessories weigh the car down. The alloy wheels on the Sport and EX's are the same design and size, as are the tires. The Sport just has them color matched black. The EX-L leather is also heavier than cloth interiors. More features = more weight.

 

Weight is the primary reason - 101 lbs. according to the Canadian Honda website. CVT transmission is the same ratio so the RPMs will be the same across the mapping range. However the the map might be different to give the car "more perceived power" than the bottom-o-barrel LX (that I have). Last year the EX wa ssimply too much of a difference for the bells it offered.

 

Check the OP attached link. There are a lot of useful spec.The EX-L weight difference to the LX as I stated is only 67 or 71 lbs, not over 100 lbs. I don't believe 100 lbs would make the LX better by 2 mpg. I suspect it is the rolling and air resistance are of the bigger and fatter tires. I got the 2017 LX CVT, which has 2 more hp than the newer models.

 

There are inconsistencies in the mileage ratings. LX and Sport have same ratings with manual but different with CVT, whereas Sport, EX and EX-L have same ratings with CVT.

It looks like they have made just one certification test with manual (Sport) and two with CVT (one with LX, another with EX-L) to cover all eight variants in the matrix. Deeper study to EPA test procedure specification would probably open some other thoughts.

 

I wonder if the big difference is that the LX has a smaller diameter and circumference tire than the LX. It's not a huge difference but possibly enough combined with the weight penalty of higher trim models. Even my EX can pull mid 40s mpgs.

 

EPA numbers are not god given numbers. We should not use them as precise values, but as an approximate guideline to what we could expect. There are many, including me, have claimed their mpg exceeded the EPA values. I suspect when EPA does a lab test there is a table to deduct value due to certain features that is not in the standard tested car. For example, if a car has a rear wing to create downforce. EPA deduct mpg for that because it is an aerodynamic drag, which a lab test cannot include in its EPA rating.

This is how EPA comes up with their numbers.
How Vehicles Are Tested. Fuel economy is measured under controlled conditions in a laboratory using a series of tests specified by federal law. ... EPA reviews the results and confirms about 15%–20% of them through their own tests at the National Vehicles and Fuel Emissions Laboratory.

 

If the tires are the same compound but different size, that will contribute to rolling resistance and impact gas mileage (MPG).

rolling resistance vs tire width

Factors for rolling resistance

 

I would not have guessed that the sun roof weighed 80 pounds. I would have guessed 40.

 

Whether LX 6spd (the proper trim), or EX-L cvt, don't forget tire pressure vs speed also greatly effects rolling resistance and subsequently MPG.




+1


On the topic of the rating system for fuel economy, TIRE ROLLING RESISTANCE PART 1: UNDERSTANDING CORPORATE AVERAGE FUEL ECONOMY.