CX-5 turbo high rpm on highway

I recently bought a 2019 CX-5 GT-R. I have a 60 mile commute, all highway, cruise set at 75 mph. I bought this as a comprise between fuel efficiency and power (turbo). I have been astonished by how bad the gas mileage is 20 - 23 highway. I can't stop looking at the tach which shows over 2500 rpm at 75 mph. It's like it needs another gear or two. I feel this is why it gets such poor highway mileage. Also, this could not be good for the longevity of the engine. Thought? I'm about ready to get rid of it after less than a month. Most uncomfortable seats I've ever experienced in a car but that's another story.
 

erhayes

Contributor
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Mazda CX-5 FWD Touring
A boxy COV at 75 mph will not get good fuel mileage. Try dropping to 70 or 65 and your mileage will jump. Ed
 
A boxy COV at 75 mph will not get good fuel mileage. Try dropping to 70 or 65 and your mileage will jump. Ed
Even at 70 the rpm's are almost 2500. That seems excessive to me. I've never had a vehicle tach that high at that speed. Seems like a lot of stress on the engine over time.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg. Plano, TX
Contributor
:
Plano, Texas, USA
It's like it needs another gear or two
Yes, Mazda needs an 8-speed automatic. Especially on 2.5T with big torque the rpm is too high for highway cruise. 6-speed is out of date!
 
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Occupied Calif.
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2019 CX 5 GT-R
Your CX 5 mileage should improve as the engine breaks in, but I'm talking 5K to 10K miles.
I don't think 2500 RPMs at 70 MPH is excessive. The engine is running at near the peak of its torque and if you need to swing out and pass another vehicle it isn't going to have to drop a gear or two like similar SUV's with an 8 speed transmission.
I have noticed a fairly large spread of MPG's in my 2019 GT-R depending upon speed.
At 70 MPH I can get 27 MPG. But on Sou Cal freeways, you often will have to stay in the slow lane at 70 MPH as most traffic is moving at 80-85. When it isn't at a standstill anyway.
At 80 MPH average for close to 75 miles, I only got about 24 MPG.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg. Plano, TX
Contributor
:
Plano, Texas, USA
Yes, Mazda needs an 8-speed automatic. Especially on 2.5T with big torque the rpm is too high for highway cruise. 6-speed is out of the date!
Mazda at least should modify the gear ratio on its 6-speed for CX-5 2.5T, not just “re-use” everything Including the gear ratio designed for CX-9 which is much heavier!
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg. Plano, TX
Contributor
:
Plano, Texas, USA
Your CX 5 mileage should improve as the engine breaks in, but I'm talking 5K to 10K miles.
I’ve heard this break-in theory many times. But from my personal experience this has never happened. My 2016 CX-5 got 25.5~26.5 for city driving, and 27~28.5 on the highway driving at 75~80 mph when it was brand new. The mpg is still the same at 45K miles now.

To me, on the same model each car’s mpg still varies. The mpg is decided when it’s new and won’t be changed too much unless the car has developed some problems.
 

mazdadude

ZOOOOOOOOOM ZOOOOOOOOOOOM
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'16.5 Mazda CX-5 Touring
I think that if 2500 rpm feels high to you, then you might not have owned many 4 cyl vehicles before.

My first gen MX-5 Miata's would be around 4000 RPM at 70mph. :)

However, I too, am ready for the next version of the SKYACTIV transmission as well.
 
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'16.5 Mazda CX-5
Even at 70 the rpm's are almost 2500. That seems excessive to me. I've never had a vehicle tach that high at that speed. Seems like a lot of stress on the engine over time.
That is not high RPM. It will not damage or wear the engine unusually, as long as you gently warm it up. My Miata runs 3700 at 75 and gets 28+ mpg doing it. I think my CX-5 runs about the same RPM and I'm getting 26+ at 84 mph on cruise. I have a ScanGauge and can watch engine and trans temps. Mine takes 7 gentle miles to get the water temp to 180F. It takes another 20 miles to get the trans to 180F.

Check your mileage manually, rather then believing the computer. Give it 3k to 5k miles to hit peak fuel economy.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg. Plano, TX
Contributor
:
Plano, Texas, USA
I think that if 2500 rpm feels high to you, then you might not have owned many 4 cyl vehicles before.

My first gen MX-5 Miata's would be around 4000 RPM at 70mph. :)

However, I too, am ready for the next version of the SKYACTIV transmission as well.
Yeah, but the 2.5T is a different animal. None of the 4 cylinders you mentioned has a peak torque of 310 lb-ft way down at 2,000 rpm. Ideally the rpm on CX-5 2.5T at highway 75 mph cruising speed should be around 2,000 for the highest torque and the best fuel efficiency.

33C6EEE3-DB85-491C-8F6D-2EDCEE91CCF5.png
 
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CX5 GT-R
I have a 2019 cx5 gtr. Lifetime average is 26.7mpg (41k miles now).
Road trips at 75-85mph average 27-28.5mpg over 5-600mi.
 
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Texas
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'20 CX-5 Signature
hought? I'm about ready to get rid of it after less than a month. Most uncomfortable seats I've ever experienced in a car but that's another story.
Dump it! Life's too short to drive something that isn't comfortable and doesn't operate how you think it should. :)

Yes, Mazda needs an 8-speed automatic. Especially on 2.5T with big torque the rpm is too high for highway cruise. 6-speed is out of date!
I'll take a well-seasoned 6-speed over an all-new 8-speed any day. :)

The 9-speed in some of Honda's current models actually gets lower fuel economy than the 6-speed it replaces in some configurations, doesn't shift as well, costs more to maintain, and offers no significant improvement in performance and actually a decrease in performance at some passing speeds.

Your CX 5 mileage should improve as the engine breaks in, but I'm talking 5K to 10K miles.
I don't think 2500 RPMs at 70 MPH is excessive. The engine is running at near the peak of its torque and if you need to swing out and pass another vehicle it isn't going to have to drop a gear or two like similar SUV's with an 8 speed transmission.
I have noticed a fairly large spread of MPG's in my 2019 GT-R depending upon speed.
At 70 MPH I can get 27 MPG. But on Sou Cal freeways, you often will have to stay in the slow lane at 70 MPH as most traffic is moving at 80-85. When it isn't at a standstill anyway.
At 80 MPH average for close to 75 miles, I only got about 24 MPG.
Out of 40 automobiles and motorcycles so far - most of which were new and that I've kept fuel economy records for - I've never experienced an increase in fuel economy over time. In fact, my best fuel economy is generally the first tank or two after which it drops slightly and stays the same.

The V6 engine in a new 2008 Infiniti G35 I bought turned 3,000 RPM @ 70 MPH, but the redline was 7,600. :)
 
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CX5 GT-R
Dump it! Life's too short to drive something that isn't comfortable and doesn't operate how you think it should. :)



I'll take a well-seasoned 6-speed over an all-new 8-speed any day. :)

The 9-speed in some of Honda's current models actually gets lower fuel economy than the 6-speed it replaces in some configurations, doesn't shift as well, costs more to maintain, and offers no significant improvement in performance and actually a decrease in performance at some passing speeds.



Out of 40 automobiles and motorcycles so far - most of which were new and that I've kept fuel economy records for - I've never experienced an increase in fuel economy over time. In fact, my best fuel economy is generally the first tank or two after which it drops slightly and stays the same.

The V6 engine in a new 2008 Infiniti G35 I bought turned 3,000 RPM @ 70 MPH, but the redline was 7,600. :)
I recall my vq37 being rpm happy as well, while my ls7 turned a sedate 2k at 80ish.

The turbo cx5 engine isnt producing boost at cruising throttle input. Its actually just lower compression 2.5 base model engine at low throttle input, so it makes total sense to use the same highway gearing.

I, too, have never seen a vehicle get better mpg with miles. That said, my ls7 did burn oil for the first few hundred miles, then the rings seated and it stopped dropping oil level, and stopped sooting up the tail pipes.
 
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Pueblo county CO
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CX-5 Sport 16.5 6M
Some of the recent 'improvements' like CVT s and 8 or 9 sp transmissions might give slightly better CAFE numbers but I wonder how much they help in real use.
There is more than one way to influence people. Like the 'carrot' and the 'stick' can be used to get the same result.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg. Plano, TX
Contributor
:
Plano, Texas, USA

The V6 engine in a new 2008 Infiniti G35 I bought turned 3,000 RPM @ 70 MPH, but the redline was 7,600. :)
All naturally aspirated engines, including the V6 on your 2008 Infiniti G35, have the maximum torque at 3,500 ~ 4,500 rpm; but Mazda’s 2.5T has a peak torque of 310 lb-ft way down at 2,000 rpm. And the highway cruising speed should be built around 2,000 rpm with the maximum torque and the best fuel economy. Lower rpm on highway cruise also helps the longevity of the engine life.
 

erhayes

Contributor
:
Mazda CX-5 FWD Touring
I think we need to be aware of the fact that the torque at a given rpm on graphs is at WOT and not at the speed we are cruising at. Maximum efficiency is at max hp/lb of fuel consumed and is usually at the max torque at WOT.
 
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CX5 GT-R
All naturally aspirated engines, including the V6 on your 2008 Infiniti G35, have the maximum torque at 3,500 ~ 4,500 rpm; but Mazda’s 2.5T has a peak torque of 310 lb-ft way down at 2,000 rpm. And the highway cruising speed should be built around 2,000 rpm with the maximum torque and the best fuel economy. Lower rpm on highway cruise also helps the longevity of the engine life.
It's max torque is only 2000rpm under heavy boost.
 
It's max torque is only 2000rpm under heavy boost.
So does that mean if I’m cruising on the highway at a steady 65 - 70 mph and that equates to 2000 - 2500 rpm I’m at full or almost full boost my whole 60 mile drive? That seems like a recipe for poor gas mileage, short turbo and engine life.
 
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Texas
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'20 CX-5 Signature
So does that mean if I’m cruising on the highway at a steady 65 - 70 mph and that equates to 2000 - 2500 rpm I’m at full or almost full boost my whole 60 mile drive? That seems like a recipe for poor gas mileage, short turbo and engine life.
No.

An internal combustion engine is typically most efficient at wide-open throttle where pumping losses are the lowest, but that's also the point of the highest fuel consumption as well.

Let's say an engine is 45% efficient at 100% load at WOT and 25% efficient at 20% load at part-throttle.

The engine may consume 10 gallons of fuel per hour at 45% efficiency at 100% load, but only 2 gallons of fuel per hour at 25% efficiency at 20% load. Even though the engine is less efficient at part-throttle, your fuel consumption is lower.

An electric furnace is 100% efficient meaning that all of the electricity that goes into the unit is converted to heat. A gas furnace is typically 80% efficient because 20% of the heat produced by the flame is exhausted outdoors. Still, a gas furnace costs less to operate because the cost per BTU is lower.
 
No.

An internal combustion engine is typically most efficient at wide-open throttle where pumping losses are the lowest, but that's also the point of the highest fuel consumption as well.

Let's say an engine is 45% efficient at 100% load at WOT and 25% efficient at 20% load at part-throttle.

The engine may consume 10 gallons of fuel per hour at 45% efficiency at 100% load, but only 2 gallons of fuel per hour at 25% efficiency at 20% load. Even though the engine is less efficient at part-throttle, your fuel consumption is lower.

An electric furnace is 100% efficient meaning that all of the electricity that goes into the unit is converted to heat. A gas furnace is typically 80% efficient because 20% of the heat produced by the flame is exhausted outdoors. Still, a gas furnace costs less to operate because the cost per BTU is lower.
 
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