Why your fuel consumption is worse than what your car says

[nazmo]

I got a 7.6 tank. not close to manu claimed, one of my best tanks though. so super chuffed

 

[Rouxenator]

Here's an interesting experiment we did today where I was sure my 1.6 turbo with 6 speed manual would be more efficient than my wife's 1.8 with 4 speed auto.

I stuck the speed limit, she was a tad slower but not much, however over a 170km journey I used 13.5l whereas she only used 12.4l. I was paying attention to be as efficient as possible, while she was just driving like she normally does. My suspension is that because she has a bigger displacement that is naturally aspirated and the car spends most of the time in 4th, a cruising gear, it is less stressed and used less fuel than my turbo charged engine that I shift between 5/6 between ups and downs.

 

[Johnatan56]

Here's an interesting experiment we did today where I was sure my 1.6 turbo with 6 speed manual would be more efficient than my wife's 1.8 with 4 speed auto.

I stuck the speed limit, she was a tad slower but not much, however over a 170km journey I used 13.5l whereas she only used 12.4l. I was paying attention to be as efficient as possible, while she was just driving like she normally does. My suspension is that because she has a bigger displacement that is naturally aspirated and the car spends most of the time in 4th, a cruising gear, it is less stressed and used less fuel than my turbo charged engine that I shift between 5/6 between ups and downs.

What's the weight and aerodynamic difference between the cars. There is more to it than only the engine and gears.

 

[wingnut771]

Here's an interesting experiment we did today where I was sure my 1.6 turbo with 6 speed manual would be more efficient than my wife's 1.8 with 4 speed auto.

I stuck the speed limit, she was a tad slower but not much, however over a 170km journey I used 13.5l whereas she only used 12.4l. I was paying attention to be as efficient as possible, while she was just driving like she normally does. My suspension is that because she has a bigger displacement that is naturally aspirated and the car spends most of the time in 4th, a cruising gear, it is less stressed and used less fuel than my turbo charged engine that I shift between 5/6 between ups and downs.

Do it again without shifting between 5 and 6 all the time. Let her go first aswell.

 

[Willie Trombone]

There's also a big diffs between driving at 100 and 120 in some cars.

 

[Sinbad]

There's also a big diffs between driving at 100 and 120 in some cars.

All cars. Aerodynamic drag increases as the square of speed. So if your car uses x at 100km/h, it will use 1.44x at 120km/h or 44 percent more fuel to overcome the increased aero drag.

 

[Rouxenator]

I did notice that too, was averaging about 8l/100km at 120km/h until the last 50km that was on 100km/h and it pulled the average down to 7.5l/100km

What's the weight and aerodynamic difference between the cars. There is more to it than only the engine and gears.

Perhaps, we were both pretty loaded, she used a Astra H hatchback and I have a Astra J sedan. Perhaps the hatchback has a lower drag? The interwebz says the hatch has a Cd of 0.32, not sure about the sedan.

 

[wingnut771]

I did notice that too, was averaging about 8l/100km at 120km/h until the last 50km that was on 100km/h and it pulled the average down to 7.5l/100km

Perhaps, we were both pretty loaded, she used a Astra H hatchback and I have a Astra J sedan. Perhaps the hatchback has a lower drag? The interwebz says the hatch has a Cd of 0.32, not sure about the sedan.

Sedan shape is more aerodynamic than a hatchback shape afaik.

 

[Sinbad]

Sedan shape is more aerodynamic than a hatchback shape afaik.

Nope. Why do you think volvo raced 850 estates in touring cars?

 

[Moto Guzzi]

Why your fuel consumption is worse than what your car says

South Africans are subjected to fuel costs that have climbed drastically over the last decade.

During 2019, the inland price of 95 octane petrol shot up from R14.01 in January to R16.30 in December, while the prices of 93 octane and diesel have also spiked.

Weight about the same, about all vehicles I had did not pushed freely level in neutral.
If I try to push one vehicle in garage, it moves easily not expected, other vehicle sticks I have to push hard to move it, tyres correct-Why...........Bearing types used-?.......Design dif/gearbox moving parts in neutral......Why is this

 

[wingnut771]

Nope. Why do you think volvo raced 850 estates in touring cars?

 

[Hamster]

So to recap: "wife who drives slower than me uses less fuel than me"?