The Fit doesn't coast as well (in gear) as some other cars I've had, but it's not the worst, either. Of course, in neutral, it's a whole different story.

 

They exist, yes, and they are what reduces the engine's power output from the theoretical maximum. When you remove fuel from the equation in DFCO, those drag losses continue to exist. And now that they're not being overcome by burning gas, the drag on the powertrain, the braking, is now the engine's only contribution to the car's motion. You can drive forward with your foot lightly on the brake pedal too, and when you lift off the gas then the brake system's drag won't be offset by the power produced by burning gasonline any more. It's the same thing.

DFCO is a great way to spike your instant mpg, but unless you offset it by doing it on a downhill or when you want to slow/stop anyway, the overall result is a loss in mpg.

 

I use 'engine braking' to mean pumping losses that accrue from pulling air through a constricted air throttle.

Do you have data what position the air throttle is in during DFCO ?

And by the way, one test most people can do that I think is very informative is called (I think) a 'roll-down.' The idea is to get up to speed and then coast to a stop, or perhaps to a point where DFCO would cease. Since there is no fuel injection the forces operating on the car are

1. Road Friction
2. Transmission/drivetrain Friction
3. ICE Spin Friction
4. Air throttle losses

Comparing two cars on the same route would be best since it would negate the road variable. The distance is best measured with a good GPS, the altitude change by Google maps, and the start/end energy by the equations for kinetic and potential energy. Alternatively, one could measure the time to go from speed 'A' to speed 'B' rather than distance traveled.

We could also compare DFCO in gear to neutral. When I have the time I'll collect the data for our Fit and our Prius (v)agon.

In the meantime, does the ScanGauge2 have a meter for air throttle opening amount ? I presume the throttle is controlled by an ECU. Or the manifold pressure can be monitored.

 

I use "engine braking" to mean the unfueled engine's entire braking effect, be it from pumping losses or internal friction.

Coast down testing is the right way to determine how great an effect this is. You don't need two cars, just two runs. The best site for this is a downhill stretch of highway- we have mile markers down to 0.2 miles on some of our highways here and on a long, gentle hill you can pass several of them and note your speed past each one. Then simply turn around, backtrack and do it again, passing the same point at the same speed, except this time do it in Neutral. I'd expect the Prius will show less of a difference than the Fit, what with it being a hybrid and all.

Keep in mind another important force: 5. Air resistance. Keep your windows closed the whole time and if you don't have time for two runs back to back, note the outside temperature and wind, then don't count your second run against it if the conditions are much different.

I don't know where the air throttle is set during DFCO and I don't know if ScanGauge (or UltraGauge) measures it. I do have five gears and neutral, and I use each one as needed to regulate my speed. That's about as far as I worry about it.

 

Absolutely!
Amusing that I would forget that one.

 

When coasting down hill or just coasting you can down shift and the car will reduce speed, you can use it as a technique to save on brakes as well.

 

I tried that a couple of times, but I'd rather tap the brakes than rev the engine.

 

Depending on the situation, I use both techniques. If I'm moving slowly toward a stop (e.g. stoplight, stop sign, etc) and I want to keep it in DFCO, I will downshift just to keep the engine revs high enough to keep the injectors from firing, hence saving not only on brakes but fuel, too. If a light turns red and I'm not that far from it, I obviously must use the brakes, but at speed it will remain in DFCO anyway. Then as I get closer to the light and begin moving at a slower speed, I revert back to the downshifting technique above.

 

Interesting. There's also the other technique of shifting into neutral - depending on the situation. I've see the MPG go over 100 doing that.

 

I get ~270 mpg idling at 60 mph. Nice, gentle hills are your friends.

 

That would be hard to beat.

 

Only way is to shut down. Idling is still burning between 0.2 and 0.24 gallons per hour for no good reason.

 

Yep, that's where hybrids really shine, you can do engine-off neutral coasts all over town. I'm still wishing the Fit had a reasonably priced hybrid model available in the states.

 

@GoBucky
Are you neutral coasting with your CVT? I used to neutral coast in my corolla automatic w/o issues, but I keep reading mixed information about it being bad for Fit CVTs.

 

Every day.

 

Shifting back into D doesn't produce any kind of thud like I got with a regular automatic. I'll look for articles - again.

EDIT: Lots of random opinions, but this seems reliable - maybe.

"Expert: Nissan Guy replied 6 years ago.
Hello, The C.V.T. transmission will free spin when in neutral. The inside of this tranmission is made up of bands that switch from pulley to pulley depending on the speed to what gear it is in, the fluid is therefore splashing on the pulleys and bands all the time, therefore not causing any damage to the internal parts of the transmission.
Thanks.
NOTE: Do not flat tow this vehicle with all tires on ground, transfercase and transmission can be severly damaged."

 

I love contradictory advice.

 

I spoke to a friend of mine that owns/operates a transmission shop. He said you could neutral coast in the older models, but not in the 2015 CVT.

 

is this feature only in newer hondas? I coast when possible I have noticed the jazz/fit kicks up a gear when i coast downhill instead of keeping the gas down a bit otherwise the rpm gets to about 2200rpm, how do you shift into neutral while driving an auto?

 

Look for an N somewhere in the PRNDL.

The only time I saw an auto downshift down a hill was when I had the cruise on. The cruise made it downshift to try to keep me from getting too far above the speed it was set at. Killing the cruise stopped it from happening.

It wasn't in a Honda, but I can see Hondas working similarly.