What accounts for most of Fit's fuel economy?
 

I just got 41 MPG on a highway trip from Dallas to Austin. About 3.5 hours of driving. This is in a 2013 base Fit (5AT). Excellent! Of course I never see that high during my stop-and-go commute.

So on to my question: What is it that accounts for most of the Fit's decent fuel economy? Yes, I know it doesn't get the best (it lacks direct injection, for example).. But why is it as good as it is? Is it MOSTLY displacement? The fact that it has 1.5 liters and not 1.8 or 2? Simple as that? Or something more esoteric in the sensors, injectors, transmission, or something?

highway driving will net you best mpg...especially if you keep it 65mph or below.

Light weight.
Well-geared.
Tiny engine.

Its a culmination of many factors.

I actually find my Fit gets outstanding heavy traffic mileage. Not really heavy stop and go, but that traffic where you can at least coast at 15-25 mph....like 40+ mpg. Of course you have to leave room in front of you, so if everyone is pissed off and cutting each other off it does not work so well.

As said above mpg on this car is based on many factors. I find that for city driving, stop signs and long red lights hurt my mileage the most. Heavy winds on the freeway will cost me 5-7 mpg.

+1 for proper gearing. Our AT fit cruises at a ridiculously low rpm---2200rpm for 65mph. I've only ever known Hondas to be high revving buzz bombers, so this took some getting used to. B16s like to rev. This engine seems to like it low and slow.

I can noodle with timing advance in our piggyback, but 91 hates a lot of advance. 93 had more wiggle room and got maybe 2-3mpg better. I've dialed in the 91 mapping, but not the 93.

Light weight
low gearing
small engine
tire pressure
eco driving habits

Not one that is all about fuel economy but I was wondering about weight in particular so I dropped in. Getting 41mpg on the highway but when I installed 8.3lbs lighter wheel/tire combo, 20lb lighter battery, removed both rear seats and the car jack equipment, my average went up to 47-49mpg. I also was keeping gas below 50% full (Or empty depending on how you look at it), since I was doing some acceleration experiments.

I was thinking this was some kind of fluke so I didn't bother sharing. I've since installed my stock battery, both rear seats, jack assembly and full tank. It's back down in the 40-41mpg range on the highway.

No one mentioned aerodynamics. That nose shape and extreme rake of the windshield is where much of the highway mileage comes from. The boxy Scion xB has lighter weight, the same size engine with less power and it gets poorer highway mileage (real world). The Fit is no lightweight, by historical small car standards, but that only effects hill climbing and acceleration (mostly city driving).

The other thing, despite no direct injection, is the high compression ratio of the Fit engine. High compression=high efficiency. Many other details, like variable intake valve lift, also contribute.

No one mentioned aero because the aero sucks. The nose shape is deceivingly clean, it's hiding a big flat wall of a radiator and all of the air going in gets pushed under the car. The big flat rear end is an aero mess that's common on small cars because it's worth taking that hit to get more interior space.

Yeah, Honda did the best they could to teardrop the hatch area, but it's far from optimal for efficiency. The Fit EV spoiler would be cool to help with that and keep the airflow off the back of the car.

Look at the Prius (not C), that's the efficient way to design a hatchback, but you sacrifice cargo space.

Idrive the MT so mileage may vary.\

most important thing is the driver. 85K and lifetime average of the car is 44pmg. I do not drive slow and I've scared my fair share of passengers and yeah the bulk of my driving is in chicago city gridlock. Aggressive is not necessarily a bad thing. If you travel at a steady state speed. weoght will make no difference for you, otherwise it is. 2nd, you can drift a good ways and very often, even in the AT don't be afraid to drop into neutral. On MT, I'm in neutral 75% of the time.

MPG is all about the driver and what you are trying to accomplish. be specific in your exacting habits and where you want your MPG to place.

Primary reason is weight for the Fit.. secondary would be the small 1.5L..

People who think low rpms = more mpg are wrong..

Manuals rev a lot higher on the highway than the ATs, yet can turn similar if not better numbers.

Look up injector duty cycles to understand why RPM has nothing to do with MPG.

Sorry to be a D about it but the whole RPM thing is said far too often and misunderstood.