Average highway speed for high MPG drivers?

[maxwax]

I've been through 10 tanks now with my 2014 AWD Touring and I'm getting satisfying numbers: https://www.fuelly.com/driver/maxwax/cx5

However, I want better. I think the three strikes against me are:

* Driving at 5000 feet altitude in Colorado. I think I'm losing engine efficiency compared to sea-levelers.

* Driving fast (75-80 MPH) on Colorado's I-25 where the legal limit is 75MPH. I wonder if others are doing 60-70, just enough difference in speed to show some MPG gain.

* Using the AC in the hot summer while doing the above. Can't imagine this helps fuel economy, right?

Anyway, if you're tracking your fuel efficiency with something other than the onboard computer and getting impressive numbers would you share and compare your experience to mine?

Thanks!

 

[Dr_Watson]

It's kind of common sense. There is no grey area with your question! Your speed is killing your mpg. You can't change the location you drive at so forget the altitude problem, and the ac will not help either.

For the speed, select instantaneous mpg on the computer, put it in 6th and find the speed that gives max mpg. For me it's 40mph gives 76mpg uk, but I get 50mpg with mixed driving. The mpg drops dramatically, especially above 60mph. So the question is, do you save a few dollars and drive around like a potatoe or enjoy the car and sacrifice buying a Twinkie when you fill up!

 

[MikeM.]

However, I want better. I think the three strikes against me are:

* Driving at 5000 feet altitude in Colorado. I think I'm losing engine efficiency compared to sea-levelers.

* Driving fast (75-80 MPH) on Colorado's I-25 where the legal limit is 75MPH. I wonder if others are doing 60-70, just enough difference in speed to show some MPG gain.

* Using the AC in the hot summer while doing the above. Can't imagine this helps fuel economy, right?

Watson's right, your speed is killing your MPG. Aerodynamic forces increase with the square of your speed. If it was a linear relationship slower speeds would still net considerably better MPG but the quadratic nature of speed to drag really kills MPG at faster cruising speeds.

The thinner air at 5000 feet is actually working in your favor in terms of MPG because the engine management uses a barometric pressure sensor. So, while you will lose a small amount of power, your car will consume less fuel at a given rpm and throttle opening. But the MPG advantage at altitude comes from the fact that aerodynamic drag is proportional to air density. It takes less hp to push a car 60 mph in air that is less dense. And somewhere around 43 mph is the speed at which aerodynamic drag consumes more energy than rolling resistance (rolling resistance does not increase with speed - it remains constant).

The air conditioner will decrease MPG slightly but the CX-5 has an air conditioning system designed with efficiency in mind and, at freeway speeds, the a/c will affect MPG less than having the windows rolled down. The hit is very small so I never hesitate to turn it on when the alternative is to be hot and uncomfortable.

For optimum hwy MPG there are three things at the top of the list you need to keep low:

1) Speed
2) Speed
3) Speed

If you can keep these three things low you will be 90% of the way to maximizing hwy MPG. And you might find you enjoy the trip more and arrive at your destination in better spirits when you cure yourself of the terrible affliction of the "githereitus" disease. But if you have to cruise at 75mph for any reason, the Mazda 6 will crush the CX-5 with it's far superior MPG at higher speeds due to it's much more slippery aerodynamic shape. SUV shape was not designed for high speeds but for versatile cargo abilities and roomy feel for bigger bodies.

 

[xtrailman]

Its not just speed but fast acceleration, gentle throttle openings and going through the gears at the optimum time.
Anticipating traffic so avoiding heavy braking.

Approaching junctions at the correct speed so you don't have to stop, but can progress onwards.

 

[MikeM.]

Its not just speed but fast acceleration, gentle throttle openings and going through the gears at the optimum time.
Anticipating traffic so avoiding heavy braking.

Approaching junctions at the correct speed so you don't have to stop, but can progress onwards.

Yes, but that is much less of a factor on the wide open highways of the American West compared to most highways in England. We can often drive for hours without needing to slow down or change speed.

 

[TreyP]

Its not just speed but fast acceleration, gentle throttle openings and going through the gears at the optimum time.
Anticipating traffic so avoiding heavy braking.

Approaching junctions at the correct speed so you don't have to stop, but can progress onwards.

Agree. One of the dumbest things I see people do is what I call 'racing to the stop light'. When there are two lanes in the same direction and a series of stop lights, people still feel the need to go open throttle to prove they can get to that next red light before the guy in the other lane. Maybe they think that proves they have a better car, or they think someone is impressed? I don't know, but it just makes them look stupid to me.

 

[MikeM.]

One of the dumbest things I see people do is what I call 'racing to the stop light'. When there are two lanes in the same direction and a series of stop lights, people still feel the need to go open throttle to prove they can get to that next red light before the guy in the other lane.

Damn tooting! They paid a lot of extra money for the engine "upgrade" (more powerful engine) and they desperately need to find a way to utilize it! LOL!

Never mind the extra expense of brake pads, discs, tires and fuel when driving like their engine is a natural extension of their penis.

And then they wonder why they are in debt.

 

[HandA]

On my commute if I don't go over 65 on the highway portions 75% of it I can get 32-33 mpg. If I set the cruise for 70 it drops to 29-30 mpg and if I go closer to 75 it drops more from there.

If I punch it every so often to jump into an open spot in a different lane or adjust my speed more often to try to get ahead of the groups of traffic it will drop into the 26 range.

 

[dad of jon]

Damn tooting! They paid a lot of extra money for the engine "upgrade" (more powerful engine) and they desperately need to find a way to utilize it! LOL!

Never mind the extra expense of brake pads, discs, tires and fuel when driving like their engine is a natural extension of their penis.

And then they wonder why they are in debt.

in the uk the CX5 is quite a big SUV so if you're going to drive like a penis, drive a large one!

in the uk mpg=mpg at 65 my kia was at 58.

I have noticed that at 70 you'll be lucky to get anywhere near 60mpg.

 

[V8toilet]

* Driving at 5000 feet altitude in Colorado. I think I'm losing engine efficiency compared to sea-levelers.

I think you may have an advantage with slightly less air resistance.

* Driving fast (75-80 MPH) on Colorado's I-25 where the legal limit is 75MPH. I wonder if others are doing 60-70, just enough difference in speed to show some MPG gain.

Speed will kill your MPG. Although the CX5 is aerodynamic for its class it's still has significant drag compared to let's say the Mazda 6 or even your old Fit. With my 2.0 I would set the cruise control to 69 and get 35 mpg with mostly highway. With my 2.5 CX5 I have to drive a little bit slower to match that. With the cruise control I sometimes lock it in 6th gear so it doesn't automatically down shift going down hills or drop 2 gears going up hills (2.0). Also anticipating stops by looking at what traffic is doing way ahead helps me use my brakes less and keep momentum constant. The less you use your brakes and coast instead, the less fuel you will burn accelerating back to speed. There is no one magic method to getting great MPG but all the tricks summed up will net you 1-3 mpg better than the average driver gets. Using the instant display also makes you more aware of how much fuel your using.

* Using the AC in the hot summer while doing the above. Can't imagine this helps fuel economy, right?
There is a penalty but when it's 90 degrees out I don't care.

You can track both my CX5 cars in my signature and compare the two. The 2.5 only has 4000 miles on it so its only going to get better just like the 2.0 did.

 

[iced_theater]

Where I live, my commute ranges from 6100 to 6800 feet above sea level.

The past 10 tanks or so I've averaged 42.5 mpg. I've been driving 60 mph on the highway and have an overall speed average of 45 mph.

I use the A/C, have a manual tranny car, usually shift around 2200-2500 rpm. I keep my tires inflated to 40-42 psi usually, usually don't do jack rabbit starts and stops.

Pretty much all I do for my economy. I lose 2-3 mpg for every 5 mph I add onto my highway portions. Though even at 75 mph I was averaging 35 mpg combined city/highway

 

[nizzy1115]

Where I live, my commute ranges from 6100 to 6800 feet above sea level.

The past 10 tanks or so I've averaged 42.5 mpg. I've been driving 60 mph on the highway and have an overall speed average of 45 mph.

I use the A/C, have a manual tranny car, usually shift around 2200-2500 rpm. I keep my tires inflated to 40-42 psi usually, usually don't do jack rabbit starts and stops.

Pretty much all I do for my economy. I lose 2-3 mpg for every 5 mph I add onto my highway portions. Though even at 75 mph I was averaging 35 mpg combined city/highway

I agree. I can do about 40mpg with my auto sport when keeping the car between 50 and 60mph and tires at 40psi.

 

[maxwax]

You can track both my CX5 cars in my signature and compare the two. The 2.5 only has 4000 miles on it so its only going to get better just like the 2.0 did.

OK, Thanks everyone for sharing.

For the first month I was driving like grandma around town to minimize the impact of city miles. I suppose I still do, but I'm doing less so because it's soooo boring for not much of an impact on my fuel efficiency.

I think the big thing as you guys have notice is my speed. With I-25 in Colorado at a legal 75 MPH, I'm almost always do cruise control at that or a little higher and sit back. I'm going to try doing 65 in the future when I and the traffic around me can tolerate it just to see what kind of numbers I can get.

AND the next time I'm on a long road trip in scenic areas (plenty of opportunity for that out here) I'll pin it at 60-65 and run a full tank on the highway to see what I get.

v8, thanks for pointing out your Fuelly link. It's nice to see real numbers to back up the chatter you hear about good fuel efficiency while not getting it so much yourself.

 

[ddibiase]

Yes, but that is much less of a factor on the wide open highways of the American West compared to most highways in England. We can often drive for hours without needing to slow down or change speed.

You obviously don't drive on I-95 in the Northeast, Mike! ;-) (Yes, I know you did say American West)

I typically set the cruise for about 72 MPH (although I did vary it for the first 1,000 miles) and have gotten between 28 and 30 on our green engine (around 2000 miles now). I do agree with anticipating traffic snarls and coasting down (of course, that let's in a bunch of a$$holes who cut in front $#@&%) and easy acceleration (versus putting the cruise back on when clear of traffic).

Dan D

 

[Bladecutter]

Hey Maxwax,

I had my trip last month from Denver to Kansas City and back, and the closer I got to sea level, the more the fuel economy decreased.
I pretty much locked the cruise control at 77 mph until roughly Topeka where the speed limit starts to drop as you get closer and closer to KC.

The big issue I had with the trip was the huge head wind, and really hot temps that meant that the a/c was running all the time.

The return trip had higher mpg, with them ever increasing the closer we got back to Denver.
How much was caused by the wind, and how much was that altitude difference, I just can't say.
I would really want to do the same trip on a weekend that I wasn't fighting a 35 mph headwind the whole way there.

But I do believe our gas mileage might be better here at 5k feet than at sea level, under the exact same circumstances.

BC.

 

[RedBaron]

See post on other thread: http://www.mazdas247.com/forum/show...oing-on-here&p=6209561&viewfull=1#post6209561

 

[maxwax]

I've been through 10 tanks now with my 2014 AWD Touring and I'm getting satisfying numbers: https://www.fuelly.com/driver/maxwax/cx5

However, I want better. I think the three strikes against me are:

* Driving at 5000 feet altitude in Colorado. I think I'm losing engine efficiency compared to sea-levelers.

* Driving fast (75-80 MPH) on Colorado's I-25 where the legal limit is 75MPH. I wonder if others are doing 60-70, just enough difference in speed to show some MPG gain.

I just recorded my first tank at 32.2 MPG, my highest yet. After six years of driving a little 109HP manual transmission Honda Fit and getting 32.5 week to week, I'm still surprised that a bulkier, heavier and higher CX-5 can get the about same under the right conditions.

To achieve this I followed posters advice and set the cruise control when possible to 60 MPG on highway trips and just sat back.

A regular trip for me is from Fort Collins, CO to Denver Co, about 66 miles each way. When headed down during the day, 60MPG can be a frustration for the other drivers around me. But at night its no problem and only costs me a small amount of time.

Thanks again to all the other posters for valuable information like this!

 

[Bladecutter]

To achieve this I followed posters advice and set the cruise control when possible to 60 MPG on highway trips and just sat back.

A regular trip for me is from Fort Collins, CO to Denver Co, about 66 miles each way. When headed down during the day, 60MPG can be a frustration for the other drivers around me. But at night its no problem and only costs me a small amount of time.

Thanks again to all the other posters for valuable information like this!

Let me know how you set the cruise control for 60 MPG, as I've really only ever got it to about 33 MPG.
And the other drivers are just jealous about the 60 MPG you're getting. I know I am.

BC.

 

[dad of jon]

I have found I get better MPG when I switch CC off. I let the car slow a bit going uphill.

With CC it can't tell when a hill is ahead and uses more fuel keeping a constant speed uphill. I tend to ease off near the crest of a hill, and let the car catchup itself going downhill. I reckon I get 3-4 mpg more by not using CC.

 

[xtrailman]

I'm sure I read in the manual that CC isn't recommended in hilly areas, such as Wales?