Is it normal for MPG to greatly decrease after 70+ mph

Yep. Over 80mph my mpg goes from near 12 to 8.

 

I never go over the speed limit and I stay in the fast lane NO MATTER what!....

 

That's like a $250 ticket here

 

What I do is pull up beside a guy like you and stay right there. Good Times!

 

That's best for efficiency so others behind us can use the draft effect from us. You're welcome everyone!

 

My Ex-GF had some 22 year old kid doing some work on her sons car and he proceeded to tell me he bought an all stock 1978 RX7 that makes 100 Factory HP and does 200 MPH, Holy Crap I was biting my tongue as I tried to explain wind resistance...

 

Good idea...


https://youtu.be/U5ZWFyUC6qQ

 

That is a good wife!

 

Once a month I drive from Plano TX to Sallisaw OK. on business north on US 75 then east on I 40 exactly 250 mi door to door. Approx 3.5 Hrs with a mix of 65 to 80 MPH and small towns stops I drive a stock 2016 TRD sport access cab. automatic I get 21MPG with the A/C on and 21.5 with it off. this truck is 17 months old. and acording to every thing else I have read the 6 Sp.
would get no better.I am quite pleased with it.

 

Wind resistance is a squared power with speed. Horsepower required is a cubed function.

And always keep in mind. The Maximum speed achieved during the highway EPA cycle is 60 mph, the average is about 50mph. So if you wish to achieve the highway mpg rating...keep it around 50-60 mph.

 

Yep 50-60 mph is the EPAs magic numbers.So Ive read.

 

When I was in Idaho over a year ago and able to do over 70, mileage dropped to about 18 or 19 mpg. I routinely get around 23 to 24 doing 50 to 55 from home to town. Elevation 3800' to 3400' in town. Mileage varies at times, oxygenated gas, wind? Leaving town to go to Nevada which is a gradual elevation gain, mileage drops, but I get it back coming home.
Duane

 

My Lexus 2008 GS350 gets 30-33mpg from Irvine to San Jose at 78mph with AC on and 104F outside temp...Have done it for last 10 years.....

My 2016 Taco TRD Sport DCLB V6 3,50 gets 28.4mpg at 70mph going from Irvine to Salt Lake city.....shell regular...and AC.....Coming back, I got 23.2mpg at 68mph....winds! but over 70mph, it goes to 19.5mpg......19,250 miles now....After TS-b Rev 2, I have had no problems, except for leaking read end which was fixed under warranty and email t CEO.......Speed limit in Utah is 80mph is some places

 

Western red states, Utah, Wyoming, etc.

 

Agreed. That's not normal, OP. 15mpg at >70mph is pretty low for a stock truck. I do 80mph in my 2nd gen on the interstate and probably average 18. Against a 25mph headwind with winter gas and MAYBE it'd dip to 15 but doubtful. Summer blend with a tail wind and I can do 20mpg at 80mph.

 

Best mpg is at 50 in 5th non stop in the summer 26+mpg. Cruise control eats gas cause it maintanes speed on inclines. Forget mpg's in the winter, bad gas , long warm-ups, windy days.

 

80 MPH here in Wyoming. You just need a nice Wyoming tailwind. Got 23 MPG on my last drive at 80 mph. Then 18 on the way home. Your numbers do seem off from what I see at those speeds.

 

I'm driving a 2017 SR5 4x4 DCSB automatic with the stock tires & wheels (for now.....going with something more aggressive soon.....).

Here was a shot from my drive home from work last night.

My drive home consists of:

* 12 miles of rolling hills interstate (65-79 mph)

* 10 miles of in-town driving consisting of 10 stoplights (35-55mph)





Weather conditions of this particular drive found the temps in the low 60's and a light drizzle as the rain was stopping as I was walking across the parking lot to my Taco.




The longest non-stop drive I've made was this 311 mile trip I made last November. All but the last 10 miles of it were interstate, using the cruise control as much as possible with speeds set from 70-79mph.






I bought this truck last October and it replaced a 2007 Nissan Frontier 4x4 double cab manual 6 cylinder that I bought new and drove for 10+ years. Normal fill ups showed 16-17 mpg over the same daily commutes.