So, is there a MPH number that is the most effecient for MPG?
04-08-2003, 05:12 PM
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So, is there a MPH number that is the most effecient for MPG?
For example, if the car is going steady at 10 MPH in 1st gear or 60 MPH in 5th gear, is there a specific "most effecient" MPH? Just curious.
04-08-2003, 05:34 PM
#4
Burning Brakes
Originally posted by lou
Acura claims at 125 MPH in 6th gear will attribute to 28 MPG
Acura claims at 125 MPH in 6th gear will attribute to 28 MPG
Imagine using that as an excuse if you got pulled over. "But I was trying to conserve gas because of the war, officer!" heheh
04-08-2003, 05:50 PM
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Senior Moderator
Originally posted by mrdeeno
you can guesstimate it...it's the maximum cruising speed at the lowest engine speed. It's probably around 40mph in 5th gear.
you can guesstimate it...it's the maximum cruising speed at the lowest engine speed. It's probably around 40mph in 5th gear.
Engine (rpm) ÷ overdrive ratio ÷ rear axle ratio x 60/tire rpm = most efficient road speed (mph)
04-09-2003, 08:37 AM
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Originally posted by lou
Acura claims at 125 MPH in 6th gear will attribute to 28 MPG
Acura claims at 125 MPH in 6th gear will attribute to 28 MPG
Where does this information come from?
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04-09-2003, 08:48 AM
#8
trying to get a lil V-I
I think if you face your single speaker out the rear of your trunk, open your doors, and turn all your speakers on at full blast, I bet you could use the sound waves to drive the car forward. 
04-09-2003, 09:12 AM
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Originally posted by chikai
I think if you face your single speaker out the rear of your trunk, open your doors, and turn all your speakers on at full blast, I bet you could use the sound waves to drive the car forward.
I think if you face your single speaker out the rear of your trunk, open your doors, and turn all your speakers on at full blast, I bet you could use the sound waves to drive the car forward.
04-09-2003, 10:46 AM
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I'd guess that 55 - 60 in top gear would be the most efficient. From reading about the insight and folks that really try and get the most efficiency, the best way is not to use cruise control. Instead of constant speed, they shoot for constant engine power. In other words, when going up hills, they let their speed drop a smidge, and don't give extra gas to keep a constant 65. Going downhill, they'd let their speed go up to 70+.
All that said, I'd imagine that there is very little mpg difference in the real world, in our cars, whether the constant speed is anwhere between 50 and 75. My guess is a 1 or 2 mpg difference.
All that said, I'd imagine that there is very little mpg difference in the real world, in our cars, whether the constant speed is anwhere between 50 and 75. My guess is a 1 or 2 mpg difference.
04-09-2003, 09:26 PM
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As joeandcarol2 mentioned, Aerodynamic Drag varies with the square of the velocity of the vehicle. However, the Power required to keep the car moving varies with velocity CUBED because simplified, Power = Drag*V_car. I ran through some quick numbers 
...
assumptions:
air density = 1.225kg/m^3 (sea level)
Coefficient of Drag = 0.28
Frontal Area = 2.5 m^2
At 40mph ~3.3hp is needed just to overcome aerodynamic drag. At 65mph ~14.2hp and at 80mph ~26.3hp is used. So basically the slower you go the better... to a point. In high gear eventually if you go TOO slow, the engine will bog and not run efficiently. I have heard somewhere in the 40's(mph) is the most efficient.
I have experimented several times in my Accord going back and forth to San Diego. I typically get 10-15% better mileage going 65mph rather than 80mph (about 3-5mpg).
p.s. For a CL traveling at 125mph, 100.3hp is needed to overcome wind drag... that is about half throttle! I doubt it can get 28mpg at half throttle!
...assumptions:
air density = 1.225kg/m^3 (sea level)
Coefficient of Drag = 0.28
Frontal Area = 2.5 m^2
At 40mph ~3.3hp is needed just to overcome aerodynamic drag. At 65mph ~14.2hp and at 80mph ~26.3hp is used. So basically the slower you go the better... to a point. In high gear eventually if you go TOO slow, the engine will bog and not run efficiently. I have heard somewhere in the 40's(mph) is the most efficient.
I have experimented several times in my Accord going back and forth to San Diego. I typically get 10-15% better mileage going 65mph rather than 80mph (about 3-5mpg).
p.s. For a CL traveling at 125mph, 100.3hp is needed to overcome wind drag... that is about half throttle! I doubt it can get 28mpg at half throttle!
04-09-2003, 09:47 PM
#14
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WOW... I just got smarter!
Yeah, when the bass hits at volume 30 out of 30 I swear my car creeps a couple of inches when the foot is on the brake
Yeah, when the bass hits at volume 30 out of 30 I swear my car creeps a couple of inches when the foot is on the brake
04-10-2003, 08:48 AM
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Originally posted by joeandcarol2
You are nuts. Do you know that airspeed drag increases as the square of the speed?
Where does this information come from?
You are nuts. Do you know that airspeed drag increases as the square of the speed?
Where does this information come from?
04-10-2003, 09:49 AM
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Originally posted by CLUofI
The C5 vette gets 32 mpg at 100 mph, but that is also an engine with another hundred hp. And a taller 6th gear.
The C5 vette gets 32 mpg at 100 mph, but that is also an engine with another hundred hp. And a taller 6th gear.
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