is this right that at the same speed the consumption of gasoline in gear 4 is less than gear 5 ? if yes, why?

Question

if yes , despite the the engine rotation in gear 5 is less than gear 4 at the same speed ( ex 120 km/h ) but why the gasoline consumption in gear 5 is more than gear 4 ? ( in normal automobiles )

Answer 1

No.

Simply put, the higher the engine rotation (rpm), the more gas you're using.

The explosions in the cylinders determine the amount of rotation, and it takes more explosions (and therefore more gas) to achieve higher rotation.


"Getting into the highest gear you can, at the lowest possible speed, will save you plenty of gas.

Why? Because you use less gas when the engine is turning slowly. The slower the engine turns, the fewer the number of explosions in the cylinders. And fewer explosions means less gas consumed.

So, if you drive a manual transmission car, shift sooner. As long as the engine doesn't buck, shudder, or ping, you're fine. You'll sacrifice the ability to accelerate quickly — but you can always downshift if you need to accelerate. "

From: http://www.cartalk.com/content/features/fueleconomy/
(under "TIP don't linger in low gears")

Hope this helps!

Answer 2

Many factors come into the fuel economy equation several mentioned above You mention you travel at 120km
I have found over the years that the most economical speed for cars over 2 litre is about 90 km and under 2 litres about 80 km Other things such as tyre pressure, full fuel tank, 4 adults and all their baggage all have an effect
A recent fuel economy run saw a Daihatsu Mira do 77 mpg but that is with a professional driver

Answer 3

Depends on the speed. 5th gear is typically for higher speed cruising. If you are climbing a lot of hills, or are driving relatively slow (under 50MPH) then you may be "lugging" the engine, or making it work harder to achieve the same speed.

Since the higher the gear is typically an overdrive, the engine must work harder because the torque multiplication is less. If the engine has momentum on it's side (faster speed), then it doesn't have to work quite as hard.

I hope this clears up your confusion somewhat.

Good luck!

Answer 4

No, it is not true in general. Higher gear is more efficient only when the engine doesn't need to accelerate or work hard. If you go uphills, maintaining the same speed with a higher gear can be much less efficient

Answer 5

If the motor doesn't have enough power to pull in overdrive (5) then gas consumption goes up. My work truck is and has always been this way. I put it in high gear and it slows down. Yes, it's a real dog.