Gas Mileage- Results- 20% improvement !

[Bill in NC]

Ummmm...the BAS hybrid is much cheaper than a full hybrid.

http://en.wikipedia.org/wiki/Belt_alternator_starter

The car of the future will be starting/stopping all the time.

[M A V I C]

I wouldn't be surprised if shutting your car off while, for example, stopped at a light is illegal at least in some places. Seems pretty dangerous and you also have to take into account holding up traffic if you're not ready to go when the light turns green. If there's 10 cars behind you waiting for you to start your car and go, that's going to waste their gas.

I also don't believe that "surging and coasting" helps at all. I now use cruise control whenever possible because I've found the car's computer's ability to keep a constant speed better than mine. Gas mileage has gone up. Surging and then coasting conflicts with several laws of physics. For example, since a body in motion will stay in motion unless acted upon by an outside force, keeping the vehicle at a constant speed take much less energy than requiring the engine to create acceleration.

As far as driving as slow as possible saving gas, I disagree with that too. A transmission plays a huge role in that. Driving at 2k RPMs in 5th gear is going to get much better gas mileage at 2k RPMs in 1st gear. Additionally, most cars are tuned to get the best gas mileage at specific RPMs. Often that's around 60MPH. Surging up to 70MPH and back down to 50, repeat... just makes sure your car is never running in its optimal range.

The biggest issue I have with the "start off slow" tactic is often drivers are oblivious to how this impacts other drivers. If you "start off slow" and try to merge onto a freeway doing 25MPH, sure you may be saving gas but the 50 or so cars doing 60MPH that have to slam on their brakes, they waste a ton of energy.

That's an extreme example, but I've seen it happen. I often see people pull out of parallel parking spots, slowing getting up to speed and mean while several cars have caught up to them and had to cut their speed in half.

I wont even get into the fact that I drive because I like to drive...

[Mac1337]

I used to get about 190 miles to a tank(~17 gallons). I am now up to 230 miles to a tank, and I am squeezing every last ounce. Beyond a point the only way to save more gas is simply not driving.

[kj]

"- Coasting when possible (I drive a stick, so it' s possible)"

I tested this after Davester's recent post about coasting in neutral vs in gear. There's a hill coming home from work that I can accelerate up to 30 at the top, hit 40 by the end, and coast all the way home in neutral. Going back and forth between 5th and neutral I can see that being in 5th uses slightly less gas. But, I can't coast even close to all the way home in gear, so I have to give it more gas to get home. It has to be close to a wash. Of course, this is just my particular situation, so others are undoubtedly different.

I also do what I think you guys are calling "surge and coast". I figure out how fast I have to go to get to the next stop sign without gas. Once I know (trial and error), from a stop sign/light I accelerate quickly and coast to the next stop sign/ light. I do the same thing in less familiar places by hitting neutral when I see a red light ahead, etc. I can usually time things pretty well.

With everything it's a lot easier to coast in neutral than in gear, so I'm not going to worry about the small difference.

I get 4-5 mpg better by doing this stuff. And I have a little spirited driving mixed in there, so that's a constant. I don't think it's enough to make a big difference.

When I drove my previous car (a buick regal) one sit at a drive-thru cost me almost a whole mpg per tank. Sitting/idling sucks for mileage. kj.

[RAMd®d]

...the fuel injection on most cars will shut off the fuel flow entirely because the movement of the car keeps the engine turning.

I've never heard of this being a current feature. In fact, I thought I just read some manufacturer touting this as a new feature. It seems to me that regularly shutting of the fuel flow with the engine turning would cause an extremely lean condition would might do some harm to an engine over time.

I also think surge and coast has value when used appropriately. I commute on a freeway three times a day, sometimes for. It's almost impossible to use my cruise control because of the varying speeds of traffic flow.

But since I have OD for fourth gear (A/T) the car slows quite slowly when I take my foot off the gas. (And if the gas were shut off entirely, I'd stop a lot sooner.) A touch of the gas pedal brings me back up to speed.

On relatively flat terrain with light traffic, a cruise control will have some benefit. But given the amount of acceleration it supplies when it kicks in, it doesn't get much use in my car.

[Speedy]

With about a 15 gallon fill I'm at 650 miles to a tank. But then I drive a Diesel. Everyone should and we wouldn't need to import middle east oil.

[quote Dakota]I used to get about 190 miles to a tank(~17 gallons). I am now up to 230 miles to a tank, and I am squeezing every last ounce. Beyond a point the only way to save more gas is simply not driving.

[mikebw]

One thing that I have thought of doing but haven't really put into practice is not driving on a full tank. Reasoning is that the more gas you have the more weight you have, which in turn reduces the overall efficiency. Of course you would run out of gas more frequently, and have to refuel more, and unless you have a huge 40+ gallon tank you probably wouldn't see much of a difference anyway.