maximum MPG

[toughwimp11]

I've read or heard somewhere that cars achieve the best miles per gallon at a certain speed. I'm sure there are slight differences between cars but i think there was one speed that was generally the best, somewhere is the 40's maybe. anyone know it?

 

[randay]

The best speed to get the best MPG with any car no matter what make model size weight or any other factor, is: 0 mph.

 

[olds]

Moved from Off topic

 

[Smartazz]

Originally posted by: randay
The best speed to get the best MPG with any car no matter what make model size weight or any other factor, is: 0 mph.

No it wouldn't be because you'd cover 0 miles therefore making it 0mpg.
OP, I heard that it is around 55mph, but my car hit it at around 70mph so I've heard.

 

[Zenmervolt]

Depends on the car and on the gearing.

In general though, the best mileage is a steady speed just at the slowest you can possibly go in the highest gear. Between 35 and 45 mph typically.

If I am driving at a steady ~40 mph in my Volvo (Old EPA: 18/26, New EPA: 16/24, Commuting average: 22.5 mpg) will get 45+mpg.

Anyone who says that his or her car gets the best mileage at 55+ mph is failing to take into account the fact that they aren't driving continuously at 35-45 mph and that the starts and stops kill the fuel economy at those speeds in the real world.

ZV

 

[Smartazz]

Originally posted by: Zenmervolt
Depends on the car and on the gearing.

In general though, the best mileage is a steady speed just at the slowest you can possibly go in the highest gear. Between 35 and 45 mph typically.

If I am driving at a steady ~40 mph in my Volvo (Old EPA: 18/26, New EPA: 16/24, Commuting average: 22.5 mpg) will get 45+mpg.

Anyone who says that his or her car gets the best mileage at 55+ mph is failing to take into account the fact that they aren't driving continuously at 35-45 mph and that the starts and stops kill the fuel economy at those speeds in the real world.

ZV

Yeah, you're probably right. I mean, how often will anybody keep 35-45mph continuously, as opposed to the highway where people can maintain speeds very well.

 

[Smartazz]

http://en.wikipedia.org/wiki/Fuel_economy

Above about 30 mph (48 km/h), wind resistance becomes a dominant limiting factor, as it increases roughly with the square of the speed. By driving at 45 rather than 65 mph (72 rather than 105 km/h), wind resistance is about half, and much greater fuel economy can be achieved. Increasing speed to 90 mph (145 km/h) doubles wind resistance again, and further decreases fuel economy. In practice, rather than doubling or halving the fuel economy, the difference is actually closer to 20-30%.

Well there you go.

 

[iamwiz82]

About 35-39 for me. I can get around 120mpg in that range, using pulse and glide with no regard for other people behind me

 

[91TTZ]

Originally posted by: randay
The best speed to get the best MPG with any car no matter what make model size weight or any other factor, is: 0 mph.

No, that'll always be the worst MPG. You'll burn fuel idling and you won't go anywhere.

 

[91TTZ]

Originally posted by: Smartazz
By driving at 45 rather than 65 mph (72 rather than 105 km/h), wind resistance is about half, and much greater fuel economy can be achieved. Increasing speed to 90 mph (145 km/h) doubles wind resistance again, and further decreases fuel economy.

That sounds misleading. They make it sound like going from 45 mph to 90 mph doubles your wind resistance. That is incorrect.

 

[Zenmervolt]

Originally posted by: 91TTZ

Originally posted by: Smartazz
By driving at 45 rather than 65 mph (72 rather than 105 km/h), wind resistance is about half, and much greater fuel economy can be achieved. Increasing speed to 90 mph (145 km/h) doubles wind resistance again, and further decreases fuel economy.

That sounds misleading. They make it sound like going from 45 mph to 90 mph doubles your wind resistance. That is incorrect.

No it doesn't... It says quite clearly that going from 45 to 90 mph increases drag by 4x.

45 to 65 is a doubling.
65 to 90 is another doubling.

Therefore 45 to 90 is a quadrupling of drag.

Since speed doubles and drag quadruples, the power requirement increases by a factor of 8 (doubling multiplied by quadrupling means an increase by a factor of 8).

ZV

 

[91TTZ]

Originally posted by: Zenmervolt

Originally posted by: 91TTZ

Originally posted by: Smartazz
By driving at 45 rather than 65 mph (72 rather than 105 km/h), wind resistance is about half, and much greater fuel economy can be achieved. Increasing speed to 90 mph (145 km/h) doubles wind resistance again, and further decreases fuel economy.

That sounds misleading. They make it sound like going from 45 mph to 90 mph doubles your wind resistance. That is incorrect.

No it doesn't... It says quite clearly that going from 45 to 90 mph increases drag by 4x.

45 to 65 is a doubling.
65 to 90 is another doubling.

Therefore 45 to 90 is a quadrupling of drag.

Since speed doubles and drag quadruples, the power requirement increases by a factor of 8 (doubling multiplied by quadrupling means an increase by a factor of 8).

ZV

I agree that 4x would be the correct math, but I think that their wording wasn't very clear.

 

[Smartazz]

Originally posted by: 91TTZ

Originally posted by: Zenmervolt

Originally posted by: 91TTZ

Originally posted by: Smartazz
By driving at 45 rather than 65 mph (72 rather than 105 km/h), wind resistance is about half, and much greater fuel economy can be achieved. Increasing speed to 90 mph (145 km/h) doubles wind resistance again, and further decreases fuel economy.

That sounds misleading. They make it sound like going from 45 mph to 90 mph doubles your wind resistance. That is incorrect.

No it doesn't... It says quite clearly that going from 45 to 90 mph increases drag by 4x.

45 to 65 is a doubling.
65 to 90 is another doubling.

Therefore 45 to 90 is a quadrupling of drag.

Since speed doubles and drag quadruples, the power requirement increases by a factor of 8 (doubling multiplied by quadrupling means an increase by a factor of 8).

ZV

I agree that 4x would be the correct math, but I think that their wording wasn't very clear.

Yeah it doesn't sound very clear, but I think that Zenmervolt hit the nail on the head.

 

[A5]

Originally posted by: Smartazz

Originally posted by: randay
The best speed to get the best MPG with any car no matter what make model size weight or any other factor, is: 0 mph.

No it wouldn't be because you'd cover 0 miles therefore making it 0mpg.
OP, I heard that it is around 55mph, but my car hit it at around 70mph so I've heard.

You'd cover 0 miles, but you'd use 0 gallons (assuming you aren't just idling like an idiot), which is NaN MPG.

 

[jagec]

Originally posted by: iamwiz82
About 35-39 for me. I can get around 120mpg in that range, using pulse and glide with no regard for other people behind me

Well I can get 70MPG at 45MPH, but still beat pretty much any stock sports car if I need to, and no fanciness needed.

Interesting about the pulse and glide...I had to Google it.

 

[Gillbot]

http://www.teslamotors.com/index.php