Originally Posted By: Pop_Rivit
Originally Posted By: NHHEMI
Good ideas except #2 is not contributing to your increase in MPG(IMOA). Using CC on the highway actually helps your MPG as the vehicle maintains a steady speed at the optimum speed/RPM range for the vehicle. While you may be saving a very tiny, minute, amount of fuel going up hills and letting the engine slow down vs the CC giving it more gas to maintain speed, as you say, the CC actually would be saving you more on the flat sections than it is costing you on the hills.
That simply isn't correct in many circumstances.
I can easily gain a 2-3 MPG trip average by coasting uphill and letting gravity help with some of my acceleration downhill. While I don't advocate or practice it on the Interstate or when there is traffic on a 2 lane highway, I frequently do it on my way to town, especially early on a Saturday or Sunday when there isn't any traffic.
I take it a step further and allow my speed to drop from 60 MPH down to about 45 MPH. Then on the downhill side I gently bring the speed back up to 60 in anticipation of the next hill, trying to time it so I hit 60 just as I begin the next climb.
I'll agree that using the cruise control on relatively level terrain works best. But on my hilly drive, when conditions are right, I'll achieve a better result by using my foot and following the above technique.
2-3 MPG simply isn't "tiny, minute" amount of fuel in my book.
1st off what you are talking about is not normal driving and it takes a concentrated effort on the driver's part to achieve. Something most people would not bother with. It is also akin to hypermiling and in some states it is illegal to drive like that( minimum speed laws, laws against coasting out of gear or with no clutch, and some new specific hypermiling laws ). My comments are related to the OP's comments in which he/she states they use the accelerator manually up hills and then let off on the other side vs letting CC do it to save fuel. That is not the same thing you are talking about as you are talking about costing both sides. I stand behind my comments made when you take the OP's comments and my response on the whole.
Secondly, by your own admission, you are talking about a driving practice/technique to save fuel that is not safe for use in normal traffic so it does not apply IMO to this discussion nor to my answer which concentrates on what the average person can do driving to save fuel. Not everyone drives early in the AM or late at night when no one else is on the road to do what you posted. Try and do what you suggest around here and the Police would pull you over or the other drivers would run you over. Set CC at your optimum speed( 60 MPH +/- for most highway )and let it do it's job whenever it can be used vs you running the accelerator. Over a full tank and all of your driving it will consistantly return better MPG than the average person can do with their foot.
What you suggest may save the fuel you say it will( I have doubts it is that big of a savings but??? ). It is not a safe driving technique however for the average driver and as said in many states it is illegal to drive in that mannner as it would be considered hypermiling or it would break minimum speed laws, vehicle in gear laws, etc...
