I know that many members were expecting the US/Canadian version of the Fit to return Fuel economy numbers similar to Fit and Jazz cars sold in other parts of the world.

The EPA estimated fuel economy for the US/Canada Fit is 33 city/ 38 highway while cars sold in other countries are rated around 34 urban / 46 mpg highway.

When I first looked at the specs for the US car the only thing that jumped out was the new Drive by wire engine management and the jump in curb weight ~2250 lbs to ~2550 lbs for the North American cars. I knew it could not be just the switch to the 5 speed auto since the FE numbers for the manual were the same.

So after a little digging at the specification for the JDM and NA market cars I think I have an even better reason for the decreased fuel economy.

I've seen the test of the 1.5L Jazz by TOV Asia which listed a 0-60 time of ~9.3 sec. Thats great for a car that gets 46mpg on the highway.

I think the trick that Honda has for "US" is that the NA manual transmission cars are geared to SPRINT!! They have a final drive ratio that is 8% shorter than the 5 speed used on Fit/Jazz cars sold in Europe and Asia. I doesn't end there, gears 1 through 3 are 10%, 6.5% and 6% shorter respectively, while 4th and 5th gears are the same ratio.

If the stock car managed to get to 60mph in 9.3 seconds, I think the NA Fit should be a bit quicker. But it also helps explains why the Highway fuel economy numbers are 21% lower than expected.

OK, so what does this mean to FitFreaks in the US and Canada that really want better fuel economy? Well with a little tranny work to replace the NA market Final Drive with the Final drive used in Asia and Europe it may be possible to increase the Highway fuel economy for the Car.

Sorry this will not help people that opt for the auto though but if you decide to leave the car stock it should provide performance much better than the competition in the small car segment.

Here are the ratios for the NA and JDM Honda Fit transmissions.

5-Speed Transmission NA Fit JDM Fit
Gear Ratios:
1st: 3.462 3.142
2nd: 1.870 1.750
3rd: 1.321 1.241
4th: 0.970 0.969
5th: 0.757 0.756
Reverse: 3.231 3.230
Final Drive: 4.562 4.111

 

The shorter gear ratios are there to make up for the 10% weight penalty in the US market Fit. I wouldn't expect the US Fit to be any quicker other markets, and probably a little slower. This car was never designed with US frontal and side impact regulations in mind. A lot of that extra 300 lb probably went into extra steel in the doors, A, B and C pillars and the bumpers. The extra side airbags don't weight that much.

The Jazz did well in frontal impact but not so great in side impact. Hopefully the added airbags in the US car will turn things around.
http://www.euroncap.com/content/safe...?id1=1&id2=188

 

If the ratios are shorter, I say great!

I may be the minority, but I would like a little sportiness at the expense of a little fuel economy, in addition to the practicality that the fit offers.

However, taller ratios do not necessarily equal better economy. One example was my 2000 VW Golf 2.0L. That car would cruise at 80 mph at 4000 rpm and returned 32-34 mpg.

 

Someone else sees the light...

 

Could some kind soul calculate the N.A. rpm @ 80mph for both MT/AT? Thanks.

 

I also think that Honda usually post numbers below other manufacturers. What I mean is that their numbers are closer to real world driving. I have looked at the U.S. magazines and found that Hondas usually perform within 10% of their ratings, while other manufacturers are at least 20, and in some cases 30 or more percent off their actual fuel economy. So I wouldn't worry about the figures- If you are, just don't drive with a lead foot (like me)!

 

The L15A VTEC on the US-market car has been tuned for use by 87 pump octane unleaded fuel.

People forget that in Europe, Japan, much of Southeastern Asia, Australia and New Zealand, the lowest octane fuel you can get is 93 pump octane (95 pump octane is more the norm, with 98 pump octane available as the premium fuel). Because of that, Honda could keep the compression ratio fairly high and tune the VTEC valve operation to take advantage of these higher-octane fuels. In the USA, because 87 pump octane fuel can cause pre-detonation ("knocking") problems, Honda had to probably change the compression ratio and/or adjust the VTEC valve operation to avoid this problem; unfortunately, this meant Honda had to redo all the transmission gear ratios for decent performance, which will cut the fuel economy of the car.

If Honda had been able to adapt the 1.3-liter SOHC i-VTEC engine from the 2006 Civic Hybrid (minus the IMA hardware) in 1.5-liter form, it's likely they could have gotten an engine with around 115 bhp (SAE 08/04 net) and also 2-3 mpg better overall fuel economy, since the more sophisticated valve timing function of i-VTEC could allow Honda to run higher compression ratio with 87 pump octane unleaded. As such, the L15A VTEC engine's VTEC valvetrain is probably not much different than the VTEC-E valvetrain used on my 1998 Civic HX CVT coupé.

 

So should I use a higher octane in my Fit when I get it? Sorry, my eyes glaze over when I read about compression ratios and such.

 

But, last year, Honda offered a vehicle in the USA that was rated at 36/44 city/highway mpg.

They must think we are stupid, or never knew, or forgot, or something.

This "Fit" is unfit for purchase in comparison--it's insulting to me that they have such blatant disregard for those of us who put fuel economy at the highest priority but are disinclined to take out a second mortgage to purchase a hybrid.

Oh well. It just means I'll be spending more time on my bicycle. It's good for me.

 

This is for the the Fit with 14" tires (22.95" tall) in 5th gear
Manual :
2000rpm at 54mph
3000rpm at 82mph

Automatic:
3000 rpm at 63mph
4000 rpm at 84mph

The difference between these seems really odd to me. Somebody double check my work.
http://www.et-studios.com/motorsports/gears/gears.html

 

Thanks for the link. I was interested in the 15" Sport package so I got these cruising rpms in 5th gear:

15" Wheel (23.4" tire rolling diameter):

5MT: 75mph (120kph) @ 3500rpm
5AT: 75mph (120kph) @ 2700rpm

Wow, that's a big gap. In comparison, my 99 Civic EX 5MT cruises 75mph @ 3500rpm and gets 33mpg avg. 38mpg seems quite doable, at least with the 5AT.