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Highway Fuel Economy worse than City?

metroplex

Well-Known Member
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Location
Detroit, MI
City, State
Detroit, MI
Year, Model & Trim Level
2018 Ford Explorer XLT
Anyone else notice their highway fuel economy is worse than City?

My 2018 XLT 4WD can get 17 to 18 mpg in suburban driving on warm days, like up to 55 mph in moderate stop and go. It drops to 15 to 16 in the colder or snowy conditions . But once I get on the freeway where traffic is 70+mph the fuel economy doesn't increase and actually drops fairly dramatically

I understand the SUVs are larger, heavier, with poor aerodynamics but the window sticker says up to 22 mpg highway. Are they considering 55 mph to be highway speeds?

I am using the pencil and paper method of calculating gas mileage and am running the factory tires.
 



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Mine runs in the 15s in the city, 17 mixed, and 22+ on the highway. If you haven't already, reset the mileage calculations and see what happens. Also track it manually, to make sure that's what's actually happening.
 












You also really can't go by the mileage indicator in the dash. All it does is average it out.

Get your pencil and piece of paper out and start doing the actual math to figure it out.
 






I always do the paper method and those are the results I get. I noticed the onboard system also measures fuel used and is always about 0.1 to 0.8 gal less than what the pump puts in.

I am using stock factory tires not winter tires.
 






Is your transmission shifting into OD on the highway?

This is just crazy.
 






I believe so, the RPMs aren't screaming. But I may not necessarily be on cruise control the entire time due to inconsistent traffic speeds and the ginormous potholes. I noticed that the transmission likes to downshift quite a bit during normal driving on the freeway whenever I apply a little too much throttle.
 






I always do the paper method and those are the results I get. I noticed the onboard system also measures fuel used and is always about 0.1 to 0.8 gal less than what the pump puts in.

I am using stock factory tires not winter tires.
Join Fuelly.com and you can put your pencil and paper away. It also tracks your fill ups so you can see how you are doing in regards to previous ones. I've found that the onboard Instant Mileage figure is always optimistic. When it shows an average consumption of 13L/100km it usually ends up being 12L or less.

Peter
 






Join Fuelly.com and you can put your pencil and paper away. It also tracks your fill ups so you can see how you are doing in regards to previous ones. I've found that the onboard Instant Mileage figure is always optimistic. When it shows an average consumption of 13L/100km it usually ends up being 12L or less.

Peter

Optimistic? You're being kind. lol - I choose to the use phrase complete fabrication. My Focus is off somewhere between 5-10%, and it's NEVER in the direction where I leave the station thinking, boy, Ford really understated their fuel economy.
 






Optimistic? You're being kind. lol - I choose to the use phrase complete fabrication. My Focus is off somewhere between 5-10%, and it's NEVER in the direction where I leave the station thinking, boy, Ford really understated their fuel economy.
That is about the same percentage that mine is off and it has been fairly consistent over the last 3 vehicles I've had. I only use the Instant Mileage figure displayed as a guideline. That is why I use the 'fuelly' site to get an accurate figure. I can go in and still pull up the figures for the 2011 Limited I had.

Peter
 






This is why they are called LieOmeters and all manufacturers are the same.
 






So 22 mpg is about the max I'll see with the Explorer on the freeway? I always do my own math calculated MPG and take the onboard MPG data, and log both. Have been doing this for more than 20 years. I noticed the colder it is, the worse the fuel economy. I thought it was just the turbos on my SHO, but it's the same on the Fusion Sport and this XLT. I think it is the AWD system, specifically that viscous coupler fluid and maybe the PTU/driveshaft combo. When it is the cold, that viscous coupler must be really thick and robs power to churn it.
 






So 22 mpg is about the max I'll see with the Explorer on the freeway? I always do my own math calculated MPG and take the onboard MPG data, and log both. Have been doing this for more than 20 years. I noticed the colder it is, the worse the fuel economy. I thought it was just the turbos on my SHO, but it's the same on the Fusion Sport and this XLT. I think it is the AWD system, specifically that viscous coupler fluid and maybe the PTU/driveshaft combo. When it is the cold, that viscous coupler must be really thick and robs power to churn it.
Gas mileage always deteriorates in cold weather and it doesn't matter if it is AWD, 4WD or 2WD. There are several reasons for that. Fuel Economy in Cold Weather
Also as for fuel mileage, speed is the biggest killer. Mpg For Speed - Fuel Efficiency Vs. Speed

Peter
 






I've never seen MPG vary this much with a FWD or RWD car/SUV/truck before. Which is why I suspect it is the viscous coupling system for the AWD. I have a co-worker with a Ford Edge FWD 3.5L V6 (non-EcoBoost) that was in the high 20s/low 30s MPG on the freeway (same driving conditions) and when he went to the Edge AWD w/ the 3.5L V6 (non-Eco) he too said it dropped significantly.

As soon as the weather gets above about 40F ambient, my gas mileage is noticeably better. Below 40F, even around 30F, it is just as bad as it is when it is -10F to 30F.

The AWD system is comprised of the PTU, driveshaft, viscous coupler unit, and the rear diff. On the SHO, it seems like the coupler is attached to the rear diff, but it seems like it is attached to the PTU on the Explorer because I see a big module attached to the PTU that I didn't see on the SHO? In any case, it is constantly spinning but the coupler engages the clutches when power has to be sent to the back wheels. I bet that fluid is fairly thick which could explain the much poorer fuel economy at colder temperatures. The front-wheel drive CD3/CD4/D3/D4 vehicles don't seem to have as terrible fuel economy. The EPA sticker numbers differ by only 1-2 mpg which doesn't seem right.

My other theory is the gearing on my 2018 XLT. At 80 mph, 6th gear, it is screaming at 2500 RPM. On the SHO, same speed and gear, it is running at 2000 RPM. I'd have to drive much slower than the freeway speed limits to keep the same RPM.
 






Honestly, the Explorer has proven to be no better than my Sierra 6.2L GUZZLER! Only reason I got the Explorer is because it's easier to park in the city/parking garages.
 






...........My other theory is the gearing on my 2018 XLT. At 80 mph, 6th gear, it is screaming at 2500 RPM. On the SHO, same speed and gear, it is running at 2000 RPM. I'd have to drive much slower than the freeway speed limits to keep the same RPM.
At 80 mph your fuel efficiency is 28% less that it would be at 55 and 11% less efficient than driving at 70. An AWD will get less MPG than either a FWD or RWD. That is just the way it is. I don't know how many miles you have on it buy the Manual mentions not to judge your MPG until you have at least 1000 miles on the vehicle. I'm sure that the gearing is most definitely different between the two vehicles you mention. That's normal. It will most likely be different again on the 2020 with the new transmission and reported RWD.

Peter
 






If you drive 55-70 mph on a Michigan freeway, it's like stopping in the middle of a busy road. There's no way to really drive below 70-75 mph on the highways here in Michigan. Like I said, at 80 mph, the engine is screaming at 2500 RPM. I'd have to drop it down to 60 mph to stay around 2000 RPM. If I lived in Maryland or New Jersey where the highways are 55-60 mph, then yes I could see much better MPG numbers.

It looks like the 10-speed auto isn't doing that much of a difference in gas mileage, and that's supposed to be the transmission they will use in the 2020 CD6 based Explorer, along with the 3.3L PDFI engine as the base engine.
2017 Ford F-150 3.5L EcoBoost 10-Speed Automatic Test | Review | Car and Driver
 






Your about 100 rpm higher than a 2nd 5.0L with 3.73 gears and 30 inch tire @80mph. Some 4 cylinder cars would be closer to 3000rpm at 80mph.

50-60mph is the sweet spot for mpg on most vehicles. Drag compounds after that as peterk mentioned. Along with what was already mentioned (winter temps/fuel/speed) you might want to check your tire pressure i you haven't all winter. They lose pressure in the colder temperatures.
 






I check my pressure every month on the dot, and I compensate for temperature changes. I also noted that my tires lose exactly 1 psi every month after compensating for temperature changes (if any).

My 18 XLT is a base model (no SYNC3) so I have the base dashboard/cluster, kind of like the Police Interceptor. So the instantaneous digital MPG display is hidden deep within the Fuel Economy mode. Out of curiosity, I drove on the local roads and noted that at 55 mph, my instantaneous MPG hovered around 20-22 mpg on flat terrain. The faster I went (up to 60 mph) the lower the fuel economy. But at 40-45 mph, it goes way up around 28-30 mpg. These aren't spikes, but rather constant readings (I know when DFCO kicks in).
 



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Alrighty..

I guess then there's nothing left to do but slow-the-fruck-down to get the mpg your looking for.

:laugh:
 






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