Graph: mpg vs mph

G

Guest2019C20

https://flic.kr/p/R9ut1s

I'm very surprised by how straight a line this is. The Impreza dropped like a rock at higher speeds.

For future reference, the car has 400 miles on it, and the temp was 27 degrees fahrenheit.
 
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Not quite sure what your point is. Anyone who's owned a CX-5 for any length of time knows that, MPG-wise, it's happiest in the 60-65 mph range (as far as highway mileage goes). Your graph appears to confirm that, with mileage dropping off beyond that point. BTW, with 400 miles on the motor, you're not even broken in yet. Your mileage will improve after the first 5k miles or so (assuming you use Mazda super moly oil).
 
Not quite sure what your point is. Anyone who's owned a CX-5 for any length of time knows that, MPG-wise, it's happiest in the 60-65 mph range (as far as highway mileage goes). Your graph appears to confirm that, with mileage dropping off beyond that point. BTW, with 400 miles on the motor, you're not even broken in yet. Your mileage will improve after the first 5k miles or so (assuming you use Mazda super moly oil).

The point was actual data. As far as your statement that it's 'happiest 60-65', I don't know what you mean. It clearly isn't more efficient there. You might have a point if mileage dropped off drastically after that, but it's a clear, linear drop. If drivers need to reclaim time, it won't cost them hugely to drive faster. If they have the option, driving slower won't drastically save them money.
 
At 85mph, I average around 16mpg. At 95mph, I average 14.7ish. I do not know what the wind-speed or direction...or if any, was, at the time. Each was measured over 25 miles of travel with cruise control set, over relatively flat terrain. Is your graph for a manual 2.0 or something?
 
Lots of environmental variables...ambient temperature, wind speed, elevation, grade, road surface, drafting traffic...etc..

Lots of car variables... 2.0, 2.5, FWD, AWD, 17" wheels, 19" wheels, Tire PSI, Roof rack, mud guards, A/C on, Windows up or down...etc..

Your mileage may vary! (enguard)
 
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At 85mph, I average around 16mpg. At 95mph, I average 14.7ish. I do not know what the wind-speed or direction...or if any, was, at the time. Each was measured over 25 miles of travel with cruise control set, over relatively flat terrain. Is your graph for a manual 2.0 or something?

That graph is in line with my FWD 2.5. It's actually a little worse, perhaps his is AWD.
 
https://flic.kr/p/R9ut1s

I'm very surprised by how straight a line this is. The Impreza dropped like a rock at higher speeds.

For future reference, the car has 400 miles on it, and the temp was 27 degrees fahrenheit.

I noticed in your graph, you clam to include headwind in your MPH.
It's impossible to compensate for headwind in any reliable way. 60MPH in a 20MPH headwind does not equal 80MPH. Maybe it equals 67MPH on the CX-5?? Maybe it's 70? Whatever that number is, it is different for every car.

At 85mph, I average around 16mpg. At 95mph, I average 14.7ish. I do not know what the wind-speed or direction...or if any, was, at the time. Each was measured over 25 miles of travel with cruise control set, over relatively flat terrain. Is your graph for a manual 2.0 or something?

LOL.. the 2.0 manual gets a solid 35MPG at steady 70. Way higher than his graph :)

The point was actual data. As far as your statement that it's 'happiest 60-65', I don't know what you mean. It clearly isn't more efficient there. You might have a point if mileage dropped off drastically after that, but it's a clear, linear drop. If drivers need to reclaim time, it won't cost them hugely to drive faster. If they have the option, driving slower won't drastically save them money.

One day you might see what paris1 means. I've found that the fuel economy of the CX-5 can be very sensitive to speed sometimes, other times it is not so.

On long drives I've found that I'll get unbelievably excellent fuel economy (over 30MPG at 80+) until the first time I turn off the engine.
However, once I've turned the engine off and back on (say after a pee break, or fueling up) the CX-5 will now only get 25MPG at the same speed under identical conditions that it was getting 30+ before.

This effect doesn't seem to exist at lower speeds. I'll still get high 30's at 65, but after a hot restart the engine seems to not be as efficient at higher speeds.

I suspect Unobtanium's speed vs MPG tests were done with the CX-5 in its "sensitive" state
 
The trip computer is just an estimate. Over long distances (more than a single tank) they tend to be relatively accurate up to +/- 2 mpg (mine usually reads low compared to measuring at the pump). There is no way cx-500 has accurate data if he has only put 400 miles on his car. Most likely he just reset the trip drove about 25-30 miles and recorded his findings. That is anything but scientific...but it doesn't take a scientist to realize gas mileage goes down when speed goes up.

Try this instead on an empty flat highway with no wind: Run the car to empty. Measure out 1 gallon of gas and pour it in, start the car and drive at specified speed until it dies again. Repeat this but each time increase speed. Log the miles traveled at each speed. There's your accurate measurement.
 
Lot's of butt-hurt goin' on here.

For those just observing, I hope you found something useful in the post. If not, well-you got what you paid for!
 
The trip computer is just an estimate. Over long distances (more than a single tank) they tend to be relatively accurate up to +/- 2 mpg (mine usually reads low compared to measuring at the pump). There is no way cx-500 has accurate data if he has only put 400 miles on his car. Most likely he just reset the trip drove about 25-30 miles and recorded his findings. That is anything but scientific...but it doesn't take a scientist to realize gas mileage goes down when speed goes up.

Try this instead on an empty flat highway with no wind: Run the car to empty. Measure out 1 gallon of gas and pour it in, start the car and drive at specified speed until it dies again. Repeat this but each time increase speed. Log the miles traveled at each speed. There's your accurate measurement.


1 gallon? You've seen these gas tanks, right? I had a 370Z that was blind to a significant amount of fuel in the tank.

Really, I think watching the trip meter for multiple tanks is the way to go. That said, most areas don't have a place you can conveniently hit 95mph for more than say, 70-80 miles at a time.
 
1 gallon above where the car stalled out. It probably means there are a few gallons left, but if you are on flat ground it will stall out again after you've used the 1 extra gallon you put in. You won't get any more accurate unless you run new fuel lines to a 1 gallon container.
 
Well I really do wonder what kind of wind I was in to be getting 10mpg less at 85, ROFL!

Have you looked at lowering springs and a tune?

Drag increases exponentially with speed, as does power required.

(Parasite)
dragvsspeed.jpg
 
Have you looked at lowering springs and a tune?

Drag increases exponentially with speed, as does power required.

(Parasite)
dragvsspeed.jpg

Not really. My Jeep was far less aerodynamic and sat a few inches higher and got similar mileage as my CX-5 above 85. It is the lower speeds at which the CX-5 wins out. Has more to do with gearing and the engine, IMO CX5 is a citycar. Not a tourer.
 
Not really. My Jeep was far less aerodynamic and sat a few inches higher and got similar mileage as my CX-5 above 85. It is the lower speeds at which the CX-5 wins out. Has more to do with gearing and the engine, IMO CX5 is a citycar. Not a tourer.

There is a point where small engines will burn more fuel than larger engines, to make the same HP. I wouldn't want to gear the CX-5 much higher, as it would lose any ability to accelerate. My Impreza had a CVT, and ran a couple hundred RPM slower at 65 mph, than the CX-5 does. But it also would barely accelerate at highway speeds. That's one case where the CVT was awesome, as it would allow the engine to rev a couple hundred RPM more (which would vary depending on how much you added throttle), and then it would accel.
 
There is a point where small engines will burn more fuel than larger engines, to make the same HP. I wouldn't want to gear the CX-5 much higher, as it would lose any ability to accelerate. My Impreza had a CVT, and ran a couple hundred RPM slower at 65 mph, than the CX-5 does. But it also would barely accelerate at highway speeds. That's one case where the CVT was awesome, as it would allow the engine to rev a couple hundred RPM more (which would vary depending on how much you added throttle), and then it would accel.

Agreed. The CX-5 is geared correctly. It's just inefficient at higher speeds is all, due to lack of power.
 
Spent yesterday with the wife's CX-5. Decided to see how low MPG I could get.

I topped it off, then went to a drive thru to idle for a while, then full throttle starts from every light or stop sign, revving it at stop lights, several WOT runs back and forth on the freeway.

I tried as hard as I could, and was only able to get the MPG down to 15.5 mpg at the conclusion of my 40 minute sample.
 
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