Driving Technique and Drive-by-Wire

[Who]

When driving my DbW vehicle I find that once I'm in top gear my right foot is no competition for the cruise control according to my ScanGauge. I end up using the up and down buttons to keep LOD down when going up and up when going down unless it's a good coast.

No matter how steady my foot is, it always seems like it is about 10-20% worse when reading the instant MPGs off the SG. Would it be because of what the ECU is "guessing" about what my foot is telling it to it?

With the Accord, cruise is no match for my foot (which is too bad because my legs are too long for it). Anyone else finding the same things with DbW cars?

[superchow]

The automatic may actually do some engine braking on downhills when in cruise control, whereas just coasting down a hill may not do that. And when engine braking the engine stops injecting fuel - free miles!

Not sure if you manually shift into a lower gear when coasting down a hill to keep the same speed or slowing down, but it yielded great results in our "once upon a time" Oldsmobile Cutlass Ciera.

[93Cobra#2771]

I suspect the DBw is making assumptions about your driving. Assumptions based on normal drivers, not hypermilers.

How about a brief description of what you are doing when the loss occurs? Gradual inputs, or dwl? What rpm and speeds is it happening?

[jamesqf]

You might also consider that the ScanGauge is less than accurate when it comes to instant mpg - or at least that's been my experience comparing it with the OEM instant mpg display on the Insight.

[i_am_socket]

Depending on the circumstance, my cruise control is better than my foot WRT instant MPG. Driving on roads without much traffic and no real hills (not much of that 'round here, but it exists) then cruise is where it's at. Add traffic or some hill stretches for EOC or NC and then my foot is better.

Fortunately my cruise control isn't very aggressive, but it does tend to over-react to small bumps in the road.

[gascort]

My mustang did better with cruise. I suspect the computer fuel trims are different in cruise in some; from the car's standpoint, less of a chance of the throttle being opened and going lean.
...purely speculation.

[93Cobra#2771]

trims are the same in cruise vs not. Perhaps the tip in throttle transition is better with cruise than with foot.

Also, remember that cruise essentially works like pulse and glide. For example. Say cruise is set at 55. Speed needs to drop to 54 before throttle is applied. Throttle stays on till 56 is reached. Etc etc.

Food for thought...

[The Atomic Ass]

Originally Posted by 93Cobra#2771

Also, remember that cruise essentially works like pulse and glide. For example. Say cruise is set at 55. Speed needs to drop to 54 before throttle is applied. Throttle stays on till 56 is reached. Etc etc.

Food for thought...

Incorrect. The cruise control maintains a partial throttle condition, only varying the the throttle if the speed goes above or below the set point.

P&G requires disconnecting the engine to glide.

[MetroMPG]

Agreed with Atomic Ass: comparing cruise with P&G isn't right, because lifting off the throttle is not gliding.

Of these three approaches - pulse & glide, driving with load, and using cruise control - the cruise control will return the worst fuel consumption.