Originally Posted by TeaMan

This is a great thread. A lot of great information.

I have a 2020 Offroad Premium and am having what I'd call extreme poor mileage. I do have some modifications that I suspect are contributing, but they should not at the level that I'm seeing. I have a 2" leveling kit in the front and 285/70R17's KO2's. I also have a bug deflector. I do need to install a 1" body lift to stop my tires from rubbing on a sharp turn in reverse. This won't help, but do want to keep the look and like the performance of the tires. I have less than 1000 miles on it, it's still breaking in also, but still seems extreme.

My mileage is better in town/city than on the highway which is a bit confusing. I actually see the mileage in the city to be around 17MPG average and Highway drop to lower 14MPG's. Also if I drive in the 75 to 80 MPH area it drops to high 13's.

So far, I like the vehicle. It's my first, I traded a Tacoma for it. Not impressed with the power, but it does get me where I need to go.

Wondering if anyone else is seeing anything like this with the 2020.

Thanks.

Originally Posted by Bmnorm2

The absolute most effective mod you can make is the driver. I've averaged 19.9 MPG over 14k miles on my stock '21 Nightshade. My best is 24.9 MPG over 230 miles of rural highway (55mph) w/ occasional stop signs. I recently achieved 23.1 MPG over 275 miles.

The most significant factors to your fuel economy are speed and acceleration, aerodynamics, mass, and rolling resistance. The engine itself is far less significant (see naturally aspirated v6 vs v8 trucks with essentially same fuel economy rating).

The only significant factors listed above that you can easily impact are speed and acceleration.

Instead of going 80 on the highway, go 75 or 70. The drag force (aero) is approximately inversely proportional to velocity^2. Since the velocity is squared, 70mph^2 (4900) vs 80mph^2 (6400) = a 30% increase in drag force!

Instead of racing to that next light that you can see is RED, just coast to it. If someone gets in front of you before that light, ITS OKAY, you aren't going to arrive at your destination any later. You'll drastically improve your fuel economy and reduce brake and suspension wear.

Originally Posted by Pedro367

I don't know how you guys do it. I like to think of myself as a pretty "grandma like" driver and I can't get the average above 17mpg and maybe 21 on the highway. Even when it was bone stock before the 1" level and factory sized c-load KO2s (essentially still stock). 20mpg average seems borderline impossible to me. Maybe there is "grandma" and then there is "super grandma," but 3mpg gain seems crazy.

Originally Posted by Mr_Bingley

The up-n-down hills out there where you live kill the mileage I think. I live closer to the Shore and I routinely get 20 around town and 23 on the Parkway.

Originally Posted by Jetboy

If a dealer did the diffs and transfer case - it's all but guaranteed they used non-synthetic fluids to refill. Toyota uses synthetic gear lubes in all the cases. So you're going to lose some mpg from that, but probably not a lot. Maybe 1mpg.

Do you have an lift, level kit, or aftermarket roof rack? Or even a bug deflector? All of those will hurt your highway mileage. GM did a pretty good study a while back that showed that a bug deflector alone will cost about 1mpg.

The common issue on the 5vz (your 3rd gen 4R) was the O2 sensors. They could essentially wear out, but you wouldn't know because the engine wouldn't identify them as having an issue. So over time they'd slowly cause a slight rich burn condition and fuel mileage would drop. I considered it sort of like preventative maintenance on my 1996. I changed them at 150 and 200k miles. Both times I had a noticeable bump up in fuel economy after.

Those are the big ones I can think of. I don't think I'm aware of any O2 sensor issues on the 5th gens though.

The wheel bearings usually start making a lot of nose is how you know they're bad. Not from anything mpg related. If they were causing excessive drag, they'd overheat and fail pretty fast. They don't have a lot of cooling ability and the thermal runaway happens pretty quick if something goes wrong that increases friction a lot.

The one thing that can cause excess drag and you may not notice is a seized brake caliper or parking brake. After you drive next time put your hand on the wheels. The brakes will probably be kinda hot, so don't burn yourself, but feel if you can for any one of the wheels being a lot hotter than the others. That would suggest a frozen brake caliper.

Could also be your driving - style or the nature of your driving. Lots of city driving of course is going to reduce mpg. Driving north of about 90mph really kills the mpg too. The next time you're on an open stretch of highway on flat ground, reset the mpg calculator and see what it gets at 65mph. For a stock 4Runner you should get around 21mpg.

Finally - double check that your tires are inflated properly.

Those are all the ideas I know of.

Good luck.

Originally Posted by Bmnorm2

@CutthroatSlam 10% drop due to winter fuel wouldn’t be unreasonable… maybe a factor. And/or higher ethanol content (within regulation but higher than your usual station). Extreme cold temps in your area will result in lower mpg too.

Have you cleaned your injectors in awhile? Some seafoam in the tank may help.

Curious how your fuel economy will change in a few months with non winter fuel and more moderate temps.

Originally Posted by 02SE

Driving through cold, denser air, will also reduce MPG. If the 4Runner gets started to let it 'warmup' before driving, you are getting ZERO MPG during that time, which will bring the MPG average down. Not to mention all the lubricants in the driveline will be thicker due to cold temps, creating more drag, and lowering MPG further.

Cold temperatures reduce MPG all the way around. I wouldn't draw any conclusions about your MPG average, until warmer temps return.