Tennesseecmax Posted September 24, 2018 Report Share Posted September 24, 2018 Recently got back from a trip (about 600 miles) of all highway miles, my cmax is only getting 35-38 mpg on a half highway at 70 mph. The tires are aired up to 40 psi all around, just one person in the car, synthetic oil, and I run fuel injector cleaner every few tanks just for the heck of it. I set eco cruise to 70-72 and drive for hours. I am due to change the spark plugs. I hope that helps! Is there anything I can do? Or anything that might be wrong?? Quote Link to comment Share on other sites More sharing options...
homestead Posted September 24, 2018 Report Share Posted September 24, 2018 Just slow down. Look at the c-max graph below. https://priuschat.com/threads/head-to-head-c-max-mpg-shootout-vs-prius-liftback-prius-v.122688/ obob 1 Quote Link to comment Share on other sites More sharing options...
obob Posted September 24, 2018 Report Share Posted September 24, 2018 (edited) Recently got back from a trip (about 600 miles) of all highway miles, my cmax is only getting 35-38 mpg on a half highway at 70 mph. The tires are aired up to 40 psi all around, just one person in the car, synthetic oil, and I run fuel injector cleaner every few tanks just for the heck of it. I set eco cruise to 70-72 and drive for hours. I am due to change the spark plugs. I hope that helps! Is there anything I can do? Or anything that might be wrong?? Air Conditioner set on recirculate ??? Temp set on highest bearable temp ??? Center grill covers helps to keep the motor at a more optimal temperature. I set my tires to 50 psi. It has been a while since I checked the but the last time I used eco-cruise (so no coasting or drafting) on the highway with speed set at 70 using regular gas, as I recall I got 41 mpg. Edited September 24, 2018 by obob ptjones and Tennesseecmax 2 Quote Link to comment Share on other sites More sharing options...
Tennesseecmax Posted September 24, 2018 Author Report Share Posted September 24, 2018 Yes the ac is on the lowest fan speed and I actually hardly need any ac due to the lovely fall weather. The ac is on Recirculate. Can't go slower as here in TN and surrounding states people go 80+ all the time and 70 is already pushing it haha! I am going to check, and clean the EGR valve and change the spark plugs soon, hopefully this weekend actually. Maybe doing thoes two things will put me back on track. Quote Link to comment Share on other sites More sharing options...
ptjones Posted September 24, 2018 Report Share Posted September 24, 2018 With 100k ICE miles and abut 206k miles total changing the plugs didn't make a difference for me. :sad: What kind of winds did you have? Any rain? I get better MPG's driving myself over ECO Cruise. Using all my tips I usually get around 52-54 mpg at 70 mph. Although my last tank going to FL and back I only got 49.1 mpg, but I was driving up to 80 mph and it was up to 97*F had to use A/C and the humidity was bad. :sad: Paul Quote Link to comment Share on other sites More sharing options...
Tennesseecmax Posted September 24, 2018 Author Report Share Posted September 24, 2018 No wind, overcast. Man I can't get anywhere near even 45 on pure long highway trips at 70. Mind you I had 3 Prii before the cmax, so I'm not new to to hybrids or driving to get good fuel economy. I'm just kinda surprised how low the fuel economy is when just the ICE is just running along. Quote Link to comment Share on other sites More sharing options...
obob Posted September 24, 2018 Report Share Posted September 24, 2018 The C-Max is a tall car. Great for tall people but not so good for higher speed mpgs. ptjones 1 Quote Link to comment Share on other sites More sharing options...
ptjones Posted September 24, 2018 Report Share Posted September 24, 2018 No wind, overcast. Man I can't get anywhere near even 45 on pure long highway trips at 70. Mind you I had 3 Prii before the cmax, so I'm not new to to hybrids or driving to get good fuel economy. I'm just kinda surprised how low the fuel economy is when just the ICE is just running along.You don't drive a CMAX like a Prius to get good MPG's, watch my YouTube videos to learn how. http://fordcmaxhybridforum.com/topic/6568-how-to-drive-a-cmax-hybridffh-to-get-great-gas-mileage/page-1:) Paul Quote Link to comment Share on other sites More sharing options...
Tennesseecmax Posted September 24, 2018 Author Report Share Posted September 24, 2018 Yes, much different than a prius. I have watched your videos before. Very interesting but even doing that I still don't get great fuel economy Quote Link to comment Share on other sites More sharing options...
markd Posted September 25, 2018 Report Share Posted September 25, 2018 You might as well go 80mph, it makes no difference as you will still be in the 38 to 40 mpg range. These cars get their best mpg's between 30 and 55 mph. Quote Link to comment Share on other sites More sharing options...
ptjones Posted September 25, 2018 Report Share Posted September 25, 2018 Going below 70 mph makes a noticeable and 65 mph is a good compromise. Yes, much different than a prius. I have watched your videos before. Very interesting but even doing that I still don't get great fuel economyIt would be interesting to try and experiment and see what happens. First raise tire pressure to 50 psi, second don't use cruise control, third use 93 octane Premium( ethanol free would be better) and fourth keep speed below 70 mpg and would expect you should see an increase of 5 mpg. If not than I think something else is going on. Paul Quote Link to comment Share on other sites More sharing options...
Tennesseecmax Posted September 25, 2018 Author Report Share Posted September 25, 2018 I actually tired going 80-85 for about 30 mins, following a row of cars aggressively on off of the brake and throttle. I actually got close to 40 mpg. The car seemed to make more use of the hybrid system like that, charging, assisting, coating, accleration. My Prii used to do well in this type of driving too. Honestly I rarely do this and I don't like driving like that (especially for a long period of time) even though I might get better mpg going faster and driving aggressively. I like cruising at 70 haha! Quote Link to comment Share on other sites More sharing options...
Tennesseecmax Posted September 25, 2018 Author Report Share Posted September 25, 2018 I found NKG laser iridium plugs on sale, plus 20% off coupon at advance auto parts website. So got the plugs for like $5 each instead of $10. Going to change the plugs, and also going to inspect the EGR valve. Actually pretty excited. I love working on my car. I have a few project cars, but the cmax is so solid and reliable I never have to hardly touch it. Amazing car, even if it doesn't get great highway mpg! Quote Link to comment Share on other sites More sharing options...
Tennesseecmax Posted September 25, 2018 Author Report Share Posted September 25, 2018 Also, thanks for all the suggestions, and comments! Hope everyone is off to a great week Quote Link to comment Share on other sites More sharing options...
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