Gas mileage?

[Guywithface]

I'm new with mechanics and I want to learn more about cars so my question is if the perfect ratio of gas to air is one part gas 14.7 parts air and the throttle controls the amount of air the is taken into the engine then wouldn't driving faster be more fuel efficient?

And why is it that mustangs get 18-20 mpg but honda civics get 40-45 mpg even though they have the same gas to air ratio?

[JR Tigerstar]

Originally Posted by Guywithface

And why is it that mustangs get 18-20 mpg but honda civics get 40-45 mpg even though they have the same gas to air ratio?

Because Mustangs have more cylinders & bigger engine displacement.

[Blt2Lst]

Originally Posted by Guywithface

I'm new with mechanics and I want to learn more about cars so my question is if the perfect ratio of gas to air is one part gas 14.7 parts air and the throttle controls the amount of air the is taken into the engine then wouldn't driving faster be more fuel efficient?

And why is it that mustangs get 18-20 mpg but honda civics get 40-45 mpg even though they have the same gas to air ratio?

I believe that mustangs are also heavier


opcorn:

[MagicRat]

Originally Posted by Guywithface

I'm new with mechanics and I want to learn more about cars so my question is if the perfect ratio of gas to air is one part gas 14.7 parts air and the throttle controls the amount of air the is taken into the engine then wouldn't driving faster be more fuel efficient?

And why is it that mustangs get 18-20 mpg but honda civics get 40-45 mpg even though they have the same gas to air ratio?

Yes, going very slow is inefficient, but past a certain point, the losses due to the laws of physics means that higher speeds uses more power and thus consumes more fuel than going slower. This happens in 2 ways:

1. Wind resistance goes up with the cube of speed. If you double your speed, the energy lost to wind resistance goes up by eight times. For example if a car requires 10 hp to overcome the wind resistance at 50 mph, then 80 hp is required at 100 mph.

2. The kinetic energy required goes up with the square of speed. If you double your speed, the energy required to accelerate goes up by 4 times. Therefore, a faster-moving car will lose much more energy when it slows down vs a slower moving one. This would not be much of an issue if there were no stops between out starting point and our destination. But the real wold has stop signs etc which use much more fuel for a faster moving car.

[carl57]

Originally Posted by Guywithface

I'm new with mechanics and I want to learn more about cars so my question is if the perfect ratio of gas to air is one part gas 14.7 parts air and the throttle controls the amount of air the is taken into the engine then wouldn't driving faster be more fuel efficient?

And why is it that mustangs get 18-20 mpg but honda civics get 40-45 mpg even though they have the same gas to air ratio?

your question can be answered with power to weight ratios and engine displacements. the civic is much lighter has a 1.5 or so cc engine where as the mustang has between a 4.0 lier to a 5.0 liter engine and is literally built heavier. a mustang is quiter going down the road, developes less body interior squeeks than does the civic and even the interior plastics are heavier constructed. One day maybe the American cars will be mostly carbon fiber shelled who knows.