Coasting down hill

[bates]

miataz,

Cruise control is a different situation and I don't know if the coasting would apply with Cruise control activated and as VWJunky mentioned your 93 year model may or may not have the electric fuel cut off that the article refrences. I also agree with VWJunky that driving down hill at 88 MPH in neutral is dangerous regardless of what your fuel economy results are. Remember that cruise control is designed to maintain speed and will meter the fuel delivery in an attempt to maintain a steady speed, that is different than coasting where you just remove your foot from the accelerator pedal.

[Furrner]

I did some playing around with the scan gauge on the Xterra yesterday and noticed something strange. Coasting above 40 MPH in gear (auto) fuel consumption showed as 9999mpg, but below 40 it was significantly less, anywhere from 50-300 mpg. Maybe it is a speed related thing? Maybe just a Nissan thing?

[VWJunky]

Furner when it says 9999 mpg you can probaly say that it probabaly is not using any fuel.

I think i get like 4000 mpg at the slower speeds coasting and 9999 at the higher ones coasting. Either way very low consumption. I get a freak number sometimes like -9 ?? when coasting down a steep hill in gear.

later

E

[cee]

..i've noticed it's mostly a factor of the grade of the incline..at even 15-20degrees, the weight of most vehicles will cause them to accelerate downhill without any need for pedal-pushing..

..i have an automatic, and on my normal commute there are stretches of 1/2-mile or more where i know the terrain & can accelerate to about 30mph at the start & then coast the entire length..and on some of those routes there are even minor inclines that i coast over easily without losing my initial momentum..

..i don't shift into neutral, but my big concern is that i might accidentally over-shift (under-shift?) & put my car into reverse..that'd be a catastrophic & transmission-ending event..not worth the risk for even 5mpg better performance..just coasting (in gear) on decent hills is enough..

..oh, a side-note (for highway driving with its numerous dips & rises due to overpasses): it's better to increase speed going downhill (even on a very minor gradient) & then try to maintain RPM, even at the loss of MPH, on the uphill side..i've seen that i can get nearly 5mph faster (sometimes more) by nudging the accelerator on a down slope, and then just maintain RPM on the upturn (it does result in lower MPH, but less gas used, i think)..or maybe i'm over-thinking (heh!)..