Interesting driving tips.

[Mike, Lord of the Spammers!]

http://news.bbc.co.uk/1/hi/magazine/7530652.stm

Should be good for all of you oil burners out there

[kent ct]

Many years ago there was the Mobilgas Economy Run. A yearly event where all the major car makes competed. This was a time when the typical American car got about 15 miles per gallon.

One year that i remember a Lincoln v12 won in its category with about 80 mpg. Smaller cars got 100 mpg or so.

The trick was, the drivers very slowly accelerated to about 30 or 35 miles per hour then threw the car into neutral, shut off the engine and coasted down to about 5 mph, restarted the engine and repeated the above, always pretending that there was an egg between their foot and the gas pedal. Fantastic mileage was the result.

Not very practical for everyday use, but could come in handy if you are ever in the position of being about to run out of gas with the nearest gas station far away. Most people tend to speed up to reach the station before they run out which is the worst thing to do.

Richard

[J-sews]

Many years ago there was the Mobilgas Economy Run. A yearly event where all the major car makes competed. This was a time when the typical American car got about 15 miles per gallon.

One year that i remember a Lincoln v12 won in its category with about 80 mpg. Smaller cars got 100 mpg or so.

The trick was, the drivers very slowly accelerated to about 30 or 35 miles per hour then threw the car into neutral, shut off the engine and coasted down to about 5 mph, restarted the engine and repeated the above, always pretending that there was an egg between their foot and the gas pedal. Fantastic mileage was the result.

Not very practical for everyday use, but could come in handy if you are ever in the position of being about to run out of gas with the nearest gas station far away. Most people tend to speed up to reach the station before they run out which is the worst thing to do.

Richard

I thought the idea was to hurry up and get to the gas station before you run out?

[Mike, Lord of the Spammers!]

Most people tend to speed up to reach the station before they run out which is the worst thing to do.

Richard

People really do that 

[NutSAK]

The trick was, the drivers very slowly accelerated to about 30 or 35 miles per hour then threw the car into neutral, shut off the engine and coasted down to about 5 mph, restarted the engine and repeated the above, always pretending that there was an egg between their foot and the gas pedal. Fantastic mileage was the result.

Not very practical for everyday use, but could come in handy if you are ever in the position of being about to run out of gas with the nearest gas station far away. Most people tend to speed up to reach the station before they run out which is the worst thing to do.

Richard

That would also depend on how the vehicles were geared, and what type of transmission they have.  Production cars are designed to run at the most efficient rpm at about 55 mph.  Most electronically-controlled auto transmissions won't even shift into top gear until a speed of at least 45 mph is reached.  Of course, there would be much more control of the process if a manual transmission was used, and a manual would suffer less mechanical loss anyway.

[kent ct]

The trick was, the drivers very slowly accelerated to about 30 or 35 miles per hour then threw the car into neutral, shut off the engine and coasted down to about 5 mph, restarted the engine and repeated the above, always pretending that there was an egg between their foot and the gas pedal. Fantastic mileage was the result.

Not very practical for everyday use, but could come in handy if you are ever in the position of being about to run out of gas with the nearest gas station far away. Most people tend to speed up to reach the station before they run out which is the worst thing to do.

Richard

That would also depend on how the vehicles were geared, and what type of transmission they have.  Production cars are designed to run at the most efficient rpm at about 55 mph.  Most electronically-controlled auto transmissions won't even shift into top gear until a speed of at least 45 mph is reached.  Of course, there would be much more control of the process if a manual transmission was used, and a manual would suffer less mechanical loss anyway.

Good points. The old cars did have manual transmissions and also longer throw on the pistons giving more torque at low rpm so if you were gentle on the gas you could stay in high gear, at least on level roads.

I think turning off the ignition on modern cars might also lock the steering wheel which would make the practice too dangerous. Also if you were coasting downhill with the engine off the power brakes would lose power after braking a few times.

So what would be best using an auto transmission in a modern car? If you go fast enough to shift into high gear it is more efficient for the engine, but increased wind resistance might make the overall efficiency less than if you stayed at a lower speed, say 35mph. 

[Biru]

I'm currently giving a fuel-efficiency idea a chance. With the way drivers hereabouts tailgate, I figure I'll leave the car in neutral and they can push me where I want to go...

[NutSAK]

The trick was, the drivers very slowly accelerated to about 30 or 35 miles per hour then threw the car into neutral, shut off the engine and coasted down to about 5 mph, restarted the engine and repeated the above, always pretending that there was an egg between their foot and the gas pedal. Fantastic mileage was the result.

Not very practical for everyday use, but could come in handy if you are ever in the position of being about to run out of gas with the nearest gas station far away. Most people tend to speed up to reach the station before they run out which is the worst thing to do.

Richard

That would also depend on how the vehicles were geared, and what type of transmission they have.  Production cars are designed to run at the most efficient rpm at about 55 mph.  Most electronically-controlled auto transmissions won't even shift into top gear until a speed of at least 45 mph is reached.  Of course, there would be much more control of the process if a manual transmission was used, and a manual would suffer less mechanical loss anyway.

Good points. The old cars did have manual transmissions and also longer throw on the pistons giving more torque at low rpm so if you were gentle on the gas you could stay in high gear, at least on level roads.

I think turning off the ignition on modern cars might also lock the steering wheel which would make the practice too dangerous. Also if you were coasting downhill with the engine off the power brakes would lose power after braking a few times.

So what would be best using an auto transmission in a modern car? If you go fast enough to shift into high gear it is more efficient for the engine, but increased wind resistance might make the overall efficiency less than if you stayed at a lower speed, say 35mph. 

That's a good point about older engines having longer strokes and thus more torque.  It's much different than the "oversquare", short-stroked high-rpm car engines of today.

There's really no advantage to turning off the ignition in a modern, fuel-injected, manual transmission vehicle.  If you are coasting above idle RPM with your foot off the accelerator, the fuel injectors shut completely off.  So, the best thing to do when coasting is to keep the car in the highest gear that will keep the RPM above idle.  I had a friend that used to argue with me about that point, and said that he always shifted into neutral when coasting.  I tried to explain to him time and time again that if you do that, fuel must be sprayed into the cylinders to keep the engine at idle.  It never really did sink in...    

It's a good question about the auto vehicles.  My Cherokee will shift into OD (4th gear) at about 45 MPH, but then I can slow down to about 30-35 before it will downshift into 3rd gear, as long as I don't push the gas too hard.  I would suspect that driving in 4th gear at those speeds on flat ground would be fairly efficient.  Of course, that's all relative, because the old-tech AMC 4.0 Litre isn't exactly an efficient engine.  ...But it does have its fair share of torque! 

It would also depend whether your auto transmission has a lockup torque converter or not.  I'll use my Jeep as an example again, because it does have an electronic lockup.  There are roads in my hometown that are very much like a roller-coaster--straight up and down some fairly steep hills.  As I climb those hills, I use just enough gas so that I'm travelling about 30MPH at the top of the hill, then let completely off the gas.  The Jeep will shift into OD immediately under this condition, the torque converter unlocks, and I'm basically free-wheeling.  At the bottom of the hill I will be doing 45-50MPH (in a 35MPH zone  ).  Then I again apply just enough gas so that I will be travelling at 30MPH at the top of the next hill.  I'll tell you--this really pisses some people off who are following me. 

[kent ct]

The trick was, the drivers very slowly accelerated to about 30 or 35 miles per hour then threw the car into neutral, shut off the engine and coasted down to about 5 mph, restarted the engine and repeated the above, always pretending that there was an egg between their foot and the gas pedal. Fantastic mileage was the result.

Not very practical for everyday use, but could come in handy if you are ever in the position of being about to run out of gas with the nearest gas station far away. Most people tend to speed up to reach the station before they run out which is the worst thing to do.

Richard

That would also depend on how the vehicles were geared, and what type of transmission they have.  Production cars are designed to run at the most efficient rpm at about 55 mph.  Most electronically-controlled auto transmissions won't even shift into top gear until a speed of at least 45 mph is reached.  Of course, there would be much more control of the process if a manual transmission was used, and a manual would suffer less mechanical loss anyway.

Good points. The old cars did have manual transmissions and also longer throw on the pistons giving more torque at low rpm so if you were gentle on the gas you could stay in high gear, at least on level roads.

I think turning off the ignition on modern cars might also lock the steering wheel which would make the practice too dangerous. Also if you were coasting downhill with the engine off the power brakes would lose power after braking a few times.

So what would be best using an auto transmission in a modern car? If you go fast enough to shift into high gear it is more efficient for the engine, but increased wind resistance might make the overall efficiency less than if you stayed at a lower speed, say 35mph. 

That's a good point about older engines having longer strokes and thus more torque.  It's much different than the "oversquare", short-stroked high-rpm car engines of today.

There's really no advantage to turning off the ignition in a modern, fuel-injected, manual transmission vehicle.  If you are coasting above idle RPM with your foot off the accelerator, the fuel injectors shut completely off.  So, the best thing to do when coasting is to keep the car in the highest gear that will keep the RPM above idle.  I had a friend that used to argue with me about that point, and said that he always shifted into neutral when coasting.  I tried to explain to him time and time again that if you do that, fuel must be sprayed into the cylinders to keep the engine at idle.  It never really did sink in...    

It's a good question about the auto vehicles.  My Cherokee will shift into OD (4th gear) at about 45 MPH, but then I can slow down to about 30-35 before it will downshift into 3rd gear, as long as I don't push the gas too hard.  I would suspect that driving in 4th gear at those speeds on flat ground would be fairly efficient.  Of course, that's all relative, because the old-tech AMC 4.0 Litre isn't exactly an efficient engine.  ...But it does have its fair share of torque! 

It would also depend whether your auto transmission has a lockup torque converter or not.  I'll use my Jeep as an example again, because it does have an electronic lockup.  There are roads in my hometown that are very much like a roller-coaster--straight up and down some fairly steep hills.  As I climb those hills, I use just enough gas so that I'm travelling about 30MPH at the top of the hill, then let completely off the gas.  The Jeep will shift into OD immediately under this condition, the torque converter unlocks, and I'm basically free-wheeling.  At the bottom of the hill I will be doing 45-50MPH (in a 35MPH zone  ).  Then I again apply just enough gas so that I will be travelling at 30MPH at the top of the next hill.  I'll tell you--this really pisses some people off who are following me. 
[/quote
Sound like you have hit on the best method in a modern car.

Richard