I was looking for the most fuel economical speed for cars (I TRAVEL QUITE ABIT) when I came across these tips, I knew about some but I discovered some new ideas also. Hope those of us that are conscious of our cars MPG can learn a thing or two.
By the way I discovered it is economical to drive at the highest gear and your RPM should be about 2000-2500 RPM.
It is a bit long, but I encourage you to read all tru.

SOURCE: HOW STUFFS WORKS


1. Shift to Neutral When Stopped.
Notice that shifting your automatic or manual transmission into neutral calms down your engine note and drops the rpm. That saves gas. Shift into neutral even for a long traffic light.

2. Don't Rev the Engine Before Shutting Off the Ignition
Many of us learned to do this on carburetor-equipped engines in the belief that stomping the gas pedal as we turned off the switch would "prime" the carb (put a jolt of gasoline in its bowl). Most of the time, it did little or no good even for a carbureted engine.
For today's fuel-injected engines, it's a complete waste of fuel. Not only that, but the final spurt of gasoline also winds up dumped on the cylinder walls where it can wash away the essential lubricant, paving the way for increased wear.

3. Don't Race the Engine at Stoplights

4. Ease Up on the Accelerator
Fuel consumption is directly related to how hard the engine is working. Ask it to race away from a stop rather than accelerate sensibly, and you'll be visiting the gas station all too frequently. Guaranteed. Ask it to barge up a steep grade rather than feathering the throttle just enough to sustain momentum, and you'll watch the needle on your gas gauge move too quickly toward "E."
Even jabbing the accelerator during passing maneuvers or lane changes eats away at fuel economy. On the highway, zooming up to the traffic ahead, then having to hit your brakes, is a fuel-wasting exercise and a sure sign of an impatient driver. The best drivers are smooth and efficient in every move they make.

5. Lose Traction, Lose Fuel
Even if you're not trying to race away from a stop, you may find your tires slipping, especially on wet or gravel surfaces. Each time a tire slips, whatever the cause, you're losing gas mileage as well as endangering yourself. Take care when starting off on slippery or unpaved roads. Slow down on rough pavement.

6. Consider RPM and MPG
An engine's workload is determined by how fast the crankshaft is turning. The crankshaft transmits engine power to the transmission and then to the wheels, and crankshaft speed is measured in revolutions per minute, as indicated on a tachometer.
A manual transmission gives the driver full control over rpm because the driver can make the engine speed up or slow down via gear selection. The lower the gear, the higher the rpm. The higher the rpm, the more torque the engine is producing, and the more fuel it is using. Automatic transmissions take some of this control out of the driver's hands, but they, too, can be manipulated to maximize fuel efficiency.

7. Shift Smartly
With a manual gearbox, shift into the upper gears quickly. Optimal shift points vary, depending on the engine/gearing combination, but for best economy you might need to shift to second by about 15 mph, and reach top gear by the time you're traveling 30 to 35 mph.
Rule of thumb: If the engine is revving faster than necessary to sustain an even road speed, move to the next higher gear. Downshifting follows a similar standard. If the gas pedal has to stay close to the floor to maintain speed, you probably belong in the next lower gear. "Lugging" in too high a gear isn't good for the engine or your finances.

8. Watch the Tachometer
Because tachometers are no longer limited to performance models, more drivers than ever have a chance to pay attention to engine speed as well as road speed. This allows you to find the engine's most efficient rpm and stay close to that point whenever feasible. What speed is that?
The exact figure depends on the engine but is typically the speed at which it produces the greatest torque output. For economy's sake, it's generally wise to remain below 3,000 rpm most of the time and to shift into the next gear before the engine gets much beyond its optimum rpm level. Too low an engine speed does nothing for your finances, so running below 1,500 isn't ordinarily a good idea.

9. Get the Most from Your Automatic Transmission
An automatic transmission liberates you from shifting gears yourself, but nothing is free, and an engine must work a little harder and use a bit more gas to transmit power through an automatic transmission than a manual. For proof, look no further than EPA fuel economy estimates, which are invariably lower for an automatic transmission than for that same vehicle equipped with a manual transmission. Still, there are some things you can do to maximize fuel efficiency in an automatic-transmission vehicle.
During acceleration, listen as the engine note rises and then falls to get a sense of when the transmission is reaching the "top" of one gear ratio and changing down to the next lower ratio. Also, watch the needle on the tachometer climb up the rpm range and descend correspondingly. Remember, the higher the rpm, the more fuel you're burning.
Some automatic transmissions tend to stay in lower gears a little too long for peak economy. You can sometimes coax the transmission into shifting to high gear earlier than usual by letting up on the gas as you pass 30 mph or so. Then, once it's in top gear, continue to accelerate very gradually.

10. Watch That Little OD Light
Virtually all manual and automatic transmissions have an overdrive gear that can be employed to save fuel. It's usually the highest-numbered gear (or gears), and it lets the engine run at a slower speed (or lower rpm) while the car maintains the same road speed.
If you're looking to save gas, get into an overdrive gear as soon as possible and stay there until you need the extra power afforded by a lower gear.
With an automatic transmission, a lot of that decision making is out of your hands. Automatics tend to move to the highest gear on their own, precisely to save fuel; at cruising speeds, overdrive (OD) kicks in. But you can shift into and out of OD. On newer cars, it's usually done via a button on the shift lever. Typically, an "OD" light illuminates in the instrument panel when an automatic is shifted out of OD. If you have inadvertently shifted out of OD, press the button to get back in for optimal fuel economy.
Many modern automatic transmissions allow drivers to change gears manually by moving the shift lever through a separate gate. This doesn't duplicate the degree of gear control afforded by a manual transmission, but it will allow you to select a lower gear for more throttle response. Doing so increases engine rpm and burns more gas. For best fuel efficiency, shift into the highest gear whenever possible or simply shift into Drive and let the automatic do what it's designed to: Select the most economical gear at each step of the way.

11. Make Sure Nothing's Afoot
Don't drive with a foot resting on the brake pedal, however lightly. Even the slightest application of the brakes while moving will drag down fuel economy. It'll place an unnecessary burden on the engine and transmission. You'll wear out your brakes rapidly, as well.
Even when your car isn't moving, you should be thinking about ways to save gas. In our final section, we'll take a look at some ways to conserve fuel while your car is standing still.

12. Practice Mind Over MPG
We tend to allow our emotions to affect our driving. Whether you are elated or angry, calm down before getting behind the wheel.
Emotionally intense drivers are a lot more likely to engage in fuel-wasting (and dangerous) acts: gunning the engine, spinning the wheels, and worse

13. Fill the Tank Only When Needed
No point stopping for gas when there's still plenty in the tank. Let it get down to about one-quarter full. Extra stops waste time, and keeping more fuel than needed in the tank adds unwanted weight to your vehicle. A gallon of gas weighs roughly 6 pounds, and the more weight you haul around, the more fuel you'll burn.
Note that there are important exceptions to this rule. During extremely cold weather, keeping the tank near full minimizes the amount of condensation, or water, that can form in the tank. Excess condensation can promote fuel-line freeze and other problems.
Additional exceptions depend on your personal travel patterns. If you regularly drive long distances, at odd hours, in desolate conditions, or in hazardous weather, it's in your interest to keep a generous supply of gas in the tank. Plan for the unexpected.

14. Buy Gas on Cool Mornings
Liquids expand when warm, and that includes gasoline. So you actually get a bit more for the same amount of cash by buying gas when it's most dense, even though the pump shows the same total.

15. Change the Air Filter
Some experts say not to expect a huge mileage boost from keeping your engine's air filter fresh; others say a clogged air filter can reduce gas mileage by as much as 10 percent.
In any case, changing an air filter is a simple task you can perform, and a properly operating air filter is essential for keeping the engine clean inside. A clogged or really dirty air filter cuts off air to the engine, and there's no doubt that hurts performance and fuel economy.
Maintain the Cooling System
An engine that runs too cool or too hot may waste 10 to 15 percent of the fuel you put into your gas tank. Your engine's operating temperature is governed primarily by the coolant fluid and the engine's thermostat.
Coolant is a blend of antifreeze and water that helps maintain proper engine temperature in both hot and cold weather conditions. The proper coolant blend is usually a 50-50 mix of antifreeze and water. The level should be maintained as indicated on the underhood reservoir, and the coolant should look clean.
A malfunctioning thermostat might stick open, which lengthens engine warm-up time and lowers the operating temperature, both of which hamper gas mileage. It could also stick in the closed position, which can cause the engine to overheat. Watch your dashboard coolant temperature gauge as a guide. Even if your car has no gauge but a warning light, one way to discover a malfunctioning thermostat is to pay attention to your car's heater. If it isn't delivering warm air within five minutes, even in freezing weather, get that thermostat checked.

16. Check Belt Tensions
Belts that drive the air conditioner, water pump, and power-steering pump must be tight enough not to slip, but not so tight as to bind. A rule of thumb used to suggest that belts needed a half-inch of slack, but some of today's engines are more delicate. Their belts must be checked by following the manual's instructions exactly, possibly using a measuring instrument to get tension exactly right. In any case, don't forget to shut off the engine before putting your hand anywhere near a belt.

17. Pay Attention to the Brakes
Take note of suspicious symptoms. A dragging brake is not only dangerous but can also drag gas mileage down with every rotation. Brake maintenance is best left to an experienced mechanic. However, if you feel comfortable putting a corner of your car on a jack, as though you're changing a tire, give the wheel a spin to see if anything seems to be dragging. If it is, contact your mechanic. And make sure the parking brake is never left engaged when you start the car.

18. Maintain Wheel Alignment and Tire Balance
Professional equipment is needed to check these, but a misaligned front end or unbalanced tire can rob plenty of mileage. Is the car pulling to the side? Chances are a realignment is needed. Unless front wheels are pointing ahead properly, the tires might scrub against the pavement and steal fuel by straining the engine. Vibration at various road speeds suggests the need for balancing. An unbalanced tire also soaks up excess gas.

Nice one mehn. Tanx

when an article screams front page......

Bookmarked, thanks a lot, cheers!

good one bro

nice one.
Please explain to me the effect of using the car air conditioner on fuel consumption and engine life.
I use a peugeot 306,auto whose a/c doesnt cool well.I planned to get it checked but a friend advised me against that.His reason is that at the car's mileage(245,243),using the a/c will kill the engine and waste petrol.

@filcast, I will have to presume a lot about your car's current condition as a high millage does not necessary mean an over worn engine.

Does a/c affect performance?
There has been a lot of debate about A/C, car performance and fuel consumption, the compressor on any car uses some of the engine's hp, even as much as 25hp depending on the size of the compressor, that is a reduction of the available power to the wheel.
So yes the A/C does affect the performance, and in your case the drop in power will be noticeable. but if your engine is in top condition and your not into sharp/aggressive driving you hardly notice the drop in performance.

Does it affect engine life?
Personally I will say note significantly, for you to trouble yourself. However that will only hold if you keep a keen eye on your engine, learn how to feel the oil to tell when it lose it's viscosity (thickness) when this occurs change the oil even if your not yet due to change the oil yet. You can consider adding oil treatment during your next oil change. (I have a 2001 camry that has 258,000 mile and the engine is still kicking strong with full A/C, I use 3 cans of whiz oil treatment each time I change my oil) another important point is your engine idle speed with a/c, you have to adjust it so that it does not run too high (cause wear and uses up fuel) or not too low as to make the engine shudder or vibrate violently(this cause engine fatigue, excess engine wear on your piston rings and your engine seating.)

Does it affect fuel consumption?
Yes, however that varies because if your on the highway with the window up and on a/c your car ia more aerodynamically efficient (which translate to less fuel consumption) than when you have the windows down and create drag and you use more fuel to overcome the wind resistance. But in general the consumption for a well tuned engine is hardly noticeable with sensible driving.
Personally what I do is winding up and putting the a/c on 3/4 full blast, when the car is cool enough I switch the a/c off but leave the fan on till it I need to switch the a/c on to cool the interior again.

So in summary, I will say, get your a/c fixed, get and experienced mechanic to look at your car, service it regularly and watch your engines behavior like a hawk for any changes, If it smokes and has lost it compression then you may have to change the rings and have the valves and top gasket checked for leakages, also the manifold may be leaking as this can prevent sufficient air from entering the engine to ensure complete combustion. Remember if less air enters the engine more fuel is used to makeup the shortage and there is no extra power benefit for that. Get your car in top condition and get the most out of your car, what is the point of driving and sweating in traffic than spending a little and keeping yourself comfortable and refreshed.

Hope this helps some.

@kakameks,
am so grateful for your excellent response.pls can you reccommend a competent peugeot service centre in Lagos.I also want to effect extensive maintence on the car,including interior and body work.cheers.

I think there is a Peugeot thread were you can get recommendations from fellow Peugeot user who reside in lagos.
Best of luck.

Humm... i better learn how to ignore those road racers on the highway then, but darn'it it sure can be exciting making then eat your dust.

just to refresh the question about fuel consumption at half tank.

Post makes bulk sense

@ Poster, ur write up is very informative. I must commend your efforts. I myself have learnt a thing or 2. I have a friend with a 1999 camry (pencil light) with a mileage of 251011. When he drives without the ac the car moves superbly but as soon as the ac is on, the car drags and seems 2be on a heavy load. Most especially wen climbing a hilly road stretch, we noticed that switching off the ac compressor makes the car climb faster than when it is on. The engine still steams in the morning and regular oil change is done. We noticed it consumes a bit more fuel than necessary. Pls what do you advise cos my friend is thinking of disposing the car. Thank you.

There was a suggestion about a somewhat similar case for Cardoctor, he suggested adding compressor oil to your compressor to help reduce the drag on the engine. You may try that as i do not see any down side to trying that, i myself will do the same with my car, it may help with some electrical issues am having with my car.

So locate a good AC man and instruct him to add some compressor oil to your compressor.

@ kakameks highly informative posts well done!

End time tinz

*speechless*

What is Tachometer?

For my generator nko? U didn't specify in ur title that the tips were for cars alone

The terms in that write up are too much..

Ghydyon: End time tinz

Who opened your cage?

END TIME TINZ

Fuel....


I'm going to learn how to bomb...

All dis things don't mean shiit 2 me....when i sell my private jet n buy my cab I will cum read dis post

Nice write up but not that easy to understand

That's nice . . .

@Op; This is really up to date and informative...Thumbs up...I'll surely be putting some of these tips into practice....

Ok! Only 4 car owners. was thinking is for all fuel engines b4 i open thread. Wen i buy d car by tomorrow i will read it, and comment

Jodasy: Nice write up but not that easy to understand

I'm even getting confused.
Dats why I prefer practical.

Merkki: What is Tachometer?

A tachometer (revolution-counter,
Tach, rev-counter, RPM gauge) is
an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine.[1] The device usually displays the
revolutions per minute (RPM) on a
calibrated analogue dial, but digital
displays are increasingly common.
The word comes from Greek Ταχος, tachos, "speed", and metron, "measure".

SOURCE: wikipedia
*Left figure shows a tachometer that can show up to 7000 RPM...

You pple wicked o!
For an informative and brilliant post like this, I think the OP deserve more hits on the "like" button...