Hello all,

I was wondering if anybody has done any modifications to get lower highway RPMs. My work commute is mostly highway, so the 3500-4000RPM cruise is clearly suboptimal.

Possibilities I've seen discussed are larger wheels, a taller final drive gear, or a complete set of new gears. Warranty voiding aside, has anyone tried anything like this? What were your results? Did MPG improve?

Josh

 

Wow, those are pretty radical mods and not cheap unless you're a DIY guy... Wheels and gears combo depends on how much homework time you put into it. Don't know if you want to out-think those Honda engineers...

Cheapest and most direct way would be your right foot. Lift it a bit and rpm goes down, mpg goes up. Warranty stays intact.

 

Sounds like you bought a manual....one of the many reason I bought at auto (taller final gear).

 

Should have clarified, manual transmission.

Highway speeds around here tend to be 75ish, so, that's more or less set.

 

Try cruising 65ish to 70ish. Driving habits, shift points, etc. are cheap mods too... Sorry, I just find it hard to complain about a Fit's mpg...

 

Yup, same here.

 

Price we pay as manual Transmission guys. It doensn't really start getting loud until like 3.5 so I just stay a lil slower or I pump the music up more

 

I wonder how much you’d really save. You’re right that the RPMs are higher than they would be with a taller gear, but the engine needs less torque, and so less fuel is consumed with each revolution. Remember, horsepower is the product of torque and RPM, and you’ll need the same horsepower at a given speed on the highway regardless of RPM. The only savings you’d see with lower RPMs are from a slight reduction in inefficiency due to the energy required to draw the extra air through the engine. My guess is that the costs involved in the modifications you suggest would be higher than the fuel savings arising from reducing such slight inefficiencies over the life of the car.

 

You can slow down and keep right without being a hazard. I see it all the time in New England. Even 65 would probably make a big and acceptable difference.

 

Excellent point. I shall now drive my automatic locked in 4th, and my mileage should be the same. ;-)

 

Driver mod FTW

 

I drive a lot of highway also and this thread makes
me happy i got an auto.

 

My ex had a Nissan Sentra for a while (between minivans... she got tired of driving a minivan and looking like a mom... then decided she couldn't live without a minivan to haul crap around.)

Anyway, it was a terrific highway car because of the tall highway gearing. 2000 RPM at 70 mph, and there was no jerky downshift if you needed to ascend a grade or pass - just a smooth transition to a shorter ratio. It also had that soft, very French suspension thanks to its Renault genes (Wouldn't "Nevada" be an awesome name for a Renault car? Ahh, brain droppings everywhere), and a decently long wheelbase for a C-class, so it soaked up expansion joints with ease.

It was like a pint sized Buick!

 

If I remember correctly, the gearbox on the Fit RS across the pond has a 6MT for 2011 so finding someone who might be able to ship the gearbox over here might be another solution. The 5AT still has a taller top gear but it's closer from what I remember. PM 555SexyDrive as he might have more info on it.

~SB

 

I agree with pianojosh - I want/have a MT and traffic goes about 75ish here. I have a 37mi commute (each way) and winding 3500+ to do 75 gets old. Is 3200 @ 75mph too much to ask?

Good point, not a great set of solutions. I want the 6MT !!!!

 

I know it's and apples to oranges comparison, but when I traded my first motorcycle which ran at 9,100 rpm for one that runs at 5000 rpm at 70 mph. I got up to highway speed and though, "Holy Crap, it doesn't sound like I'm riding a hair dryer with handlebars!"

 

Leave home 10 minutes earlier.

 

For a car with an engine as small as the Fit, you really do not want to push it much past 65 if you are trying to save on mileage. Put on your cruise control at 65 and stay in the right hand lane. Even with the taller gearing in the AT Sport, there is a 4 mpg difference cruising at 75mph and cruising at 65mph.

The manual car not only has a shorter gear box, but it also has a bigger axle gearing. This make is more fun to drive at lower speeds, as it feels much more quick and responsive. But it also means you top out faster on the freeway.

Its only 1.5L, there is not all that much you can pull out of it.

Zach

 

I dont think PianoJosh was looking to compare and contrast obvious differences between the MT and AT, but just asking if there were any viable mods to optimize what he already has.

$.02

 

The only viable mod is to change the gearbox. (or get a different car/auto)

Increasing the size of the tires will throw off the speedo/ODO and not make much of a difference unless you go extreme. To get a 500rpm drop, you'd have to go up to 185/70/16 from the 185/55's. This would increase the overall diameter by 2" and jack the car up one full inch. Tires that size might not even work and would likely rub on the inside in tighter turns. At that point, you'd also be driving an SUV and lose economy due to the extra weight of the tire and higher stance/wind resistance not to mention safety related issues being jacked up 1" and having such high sidewalls.

Long & short... this car is not a Highway cruiser in 5MT form.

~SB