When I drive, and I know I'm going to be on a road that's level or has a downhill grade, I shift my car into neutral (I drive a Standard Transmission) and coast my way down the road. One of my coworkers was riding with me once and noticed me doing this and told me I should just floor the pedal. I explained to him that by coasting and not using extra gas to move I'm saving fuel. He tells me that the best way to save fuel is to speed up so I can get to my destination faster.

Coasting does make me slow, and his argument is that I'm burning fuel with my engine idling the entire time. And the longer I'm on the road the more fuel I'm burning. He explained to me that if I speed up I'm burning more gas per minute but I'm saving fuel because I'm not spending so much time driving….

Honestly I don't buy this at all. I'm pretty sure flooring the gas pedal all the way to my destination will cause me to burn more fuel than if I was coasting downhill. What's your opinion on this?

I know cars about as well as I know brain surgery, but I do remember something a mechanic told me once; most vehicles achieve ideal gas mileage inbetween 50-60 mph/80-95 kph.

As for me? I save gas by riding my bike.

Someone
he tells me that the best way to save fuel is to speed up so I can get to my destination faster.

Your co worker is an idiot.

Coasting and keeping revs down should help. What gets me is when people keep powering along to join the back of a queue, if cars ahead aren't going anywhere why rush to get there? keep your pace steady and don't accelerate too quickly.

Lonnehart
Coasting does make me slow, and his argument is that I'm burning fuel with my engine idling the entire time. And the longer I'm on the road the more fuel I'm burning. He explained to me that if I speed up I'm burning more gas per minute but I'm saving fuel because I'm not spending so much time driving….

Honestly I don't buy this at all. I'm pretty sure flooring the gas pedal all the way to my destination will cause me to burn more fuel than if I was coasting downhill. What's your opinion on this?

You're a clever guy man- this would be easy for you to work out: just try the different approaches on a number of occasions, making careful note of how much fuel you use each time.

I'm told that diesel engines are generally more fuel efficient, but only for longer haul journeys where there's not so much stopping and starting. Petrol engines tend to handle the ins and outs of city driving better.
That's all I have to contribute; I'm a dedicated non-driver.

Coasting in neutral can be very dangerous and is illegal in many states (and some nations like the UK). When running in neutral there is a danger it may stall without you knowing until you need something (like power steering), and the other main reason is that in neutral you haven't got power braking, which is far safer than without. Having reduced braking efficiency on a highway or downhill is an extremely stupid idea. When you are coasting the vehicle is not under your control. (An older car without power brakes isn't affected by this of course, but you'd need a pretty old vehicle.)

I don't believe it is more fuel efficient either, as an ‘idling’ level of gas is still being fed to the engine in neutral and that is not usually significantly less than would be fed to the engine running in the top gear at 50-60 mph (ideal efficieny rate).

If only the 50-60 MPH option were legal here. The highest speed I can legally drive is at 35 MPH in most places and 45 MPH in others. So I guess when my coworker tells me I should speed he means that speed range. I still think coasting is the better idea around here with the speed limit so low and our roads being dangerous in the rain (for some odd reason, I slow down even faster on wet roads even when going down a gentle downhill grade).

My car is an older car ('94 Corolla), though. My braking is the same whether I'm coasting or not. I had no idea engine power had something to do with braking though. I usually use engine power to assist my braking on steep hills by downshifting gears (and using the foot brake to keep them from overrevving).

And yes, I agree. The best way to not use fuel is to ride a bicycle. :)

My reply sounded a lot harsher than I meant it. :] Sorry bout that!

Yeah there is engine braking, but there is also power assisted braking (vs. I think hydraulic). Upon reflection the power braking is probably only affected when the power steering is affected, which would be if the engine is off- and you said you coasted in neutral, not engine-off coasting (which is crazy but I'm sure some people do).

I don't know a whole lot about cars so I should probably not simply repeat stuff that I have learned in driver's ed or whatever. :I I know it's illegal all over and that you're compromising your ability to control the car though. Actually the idling gas usage and stuff I'm pretty confident is all right too, so…. probably I'm just wrong on the power brakes bit. :]

You saying you have more control with the engine off when it's wet is pretty goddamn weird though. Unless you were oversteering or something.

Harsh? Never felt it was like that.

Nope. Never coast with the engine off. I do lose brake and steering power when I do (my brakes feel as hard as rocks when this happens and my steering gets sluggish). The fuel savings you get by coasting with the engine turned off isn't worth risking your life since you have to take time to start your engine first (the same as tailgating 2 feet from the car in front of you to get maximum fuel efficiency). Coasting in neutral is still risky since if you need that engine power in a split second you need to spend that split second getting into gear first.

And I don't get more control when I coast in the rain. Rather… I think the tire treads are somehow sucking on the water on the road, creating more friction and making me slow down even more on gentle downhill grades and level surfaces. I could lose control as the road gets steeper though so I end up putting my car in gear to slow the wheels down.

While I'm not exactly an expert with opening up a car and pointing out parts or anything, I can tell you that from a physical standpoint, your engine operates most efficiently maintaining near constant speeds. They're supposed to be built for the highway, so I'm not sure if it's possible to make a huge impact on reducing fuel consumption around a city.

To answer your second question though, the one little thing I do to save gas is to always turn off my car while waiting for someone. I used to think that idling in the parking lot was more efficient than the fuel it takes to start a car, but it turns out I was wrong on that one.

I just siphon gas out of the neighbors cars in the middle of the night. It's about the only way you can save money on gas these days.

machinehead
I just siphon gas out of the neighbors cars in the middle of the night. It's about the only way you can save money on gas these days.

Last week I walked out of my apartment to grab something from my van and I found the neighbors little (eight? nine?) daughter setting up to siphon my gas into a gas can. Her parents were no where in sight. Her parents claim they had no idea that she had been doing that, but they couldn't give me a straight answer when I asked them how their daughter knew how to siphon gas.

True story.

Want to save gas? Try putting acetone (yes, the stuff women buy to remove nail polish) into your gas tank. There's detailed instructions on it online. A ‘94 Corolla is pretty old so it may benefit like my 80’s Corvette did. Read up on it. I used it for 2 years and it never hurt my car; glad I did it.

Genejoke
What gets me is when people keep powering along to join the back of a queue, if cars ahead aren't going anywhere why rush to get there? keep your pace steady and don't accelerate too quickly.

There is hope for the human species beyond just me, I see.

And yes, I do cruise in neutral all the time. But then, it's different for us Manual Transmission drivers. We change gears regularly and easily, like breathing. Automatics drivers probably hyperventilate and get scared when they have to change gears outside of their driveway.

Someone
And yes, I do cruise in neutral all the time. But then, it's different for us Manual Transmission drivers. We change gears regularly and easily, like breathing. Automatics drivers probably hyperventilate and get scared when they have to change gears outside of their driveway.

Hah, yeah. I hate automatics, far heavier on fuel consumption too.

I get up to speed, and then i put cruise control on. when i see a light has turned red, i pop it into neutral (i have a manual) and let it cost in. i also don't gun it when the light turns green.

Ally Haert

machinehead
I just siphon gas out of the neighbors cars in the middle of the night. It's about the only way you can save money on gas these days.

Last week I walked out of my apartment to grab something from my van and I found the neighbors little (eight? nine?) daughter setting up to siphon my gas into a gas can. Her parents were no where in sight. Her parents claim they had no idea that she had been doing that, but they couldn't give me a straight answer when I asked them how their daughter knew how to siphon gas.

True story.

It's happening in a lot of places. We had people around here who wait for customers at gas stations to pay for their gas, then swoop in and pump that gas into their customized tuners. Now we've got station attendants outside all hours of the day to make sure that doesn't happen. Then there's the others who like to climb under the large SUVs and pickup trucks and drill under the tank for their gas since most of us around here have locked gas caps.

Back to the subject… Lots of things around here are probably in place to keep me from coasting for too long. For instance, nearly every time I'm going downhill there's a bit of a traffic jam. Why? Because there's a traffic light on the bottom. If there's no traffic around that light will turn red just before I get to it, destroying any downhill momentum I could've used to go uphill… :(

Not that it stopped me from doing it, but it is dangerous to coast downhill in order to use that momentum to go uphill, if there is an intersection at the bottom. Even if it's green for you. That's common sense, but y'know… it's fun to coast downhill…

I don't get why ppl want to steal gas… Even though gas is now expensive, it's still not profitable to steal it. You probably profit more from shoplifting for groceries.

But I guess stealing gas out of cars is easier, and harder to catch?

I don't realize my coasters are sticking to my glass, then I go to take a drink and they fall off. Damn nuisance.

Your co-worker is so dumb he probably eats his own poop for efficiency.


Flooring it will burn WAY more gas. The highest fuel consumption occurs in sudden acceleration, and if you're lead-footing it, you're going to put more wear and tear on your brakes anyway, in addition to using more gas. I wouldn't coast in neutral with power brakes just for safety reasons, but coasting will help, just don't coast at 10mph, that's not worth it… Here's what I do:

1.I let go of the gas and coast going down hill.
2.I ease up on the gas if there's a stop sign ahead, and coast the last 4-500 feet is feasible.
3. For red lights, same rule applies. No sense flooring it to get to a red light.

Some other fuel-saving tips:

1. Put in a K)
http://www.jaketheevilhare.com

rule of thumb: the more the accelerator is pressed, the more gas it burns.

By riding a bike.

It's made me feel so much healthier! :D