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

I live in AL and travel to central KY frequently. If you run the speed limit on I-65 (normally 65-70 depending on location) a semi or irritated driver will run right up your rear in. Normal cruising speed for me is around 80 and not in the inside lane as I'm being passed like I'm standing still!

 

everyone drives like it's a race on the highway and it's annoying as fuck. going 10 over in the slow lane with cruise control and people are still getting pissed off? just fuck off you pricks

 

he is speaking for everyone who isnt completely full of shit. i.e. you.

 

My dash MPG thing claims 20~mpg on 35~ mile drives up in the eastern slope of the Sierra range. Speed at the limit between 60-70mph. Calculation matches up fairly well with my odometer and refueling intervals.

 

im surprised it hasn’t been suggested too… though it would never pass. It would also reduce miles driven as it was a really hated speed limit.

the above being said most cars get a LOT better mileage than they did back then. Even the pickups get better. Many used to average less than 10mpg… of course they were bigger and had some really strong engines

 

How am I full of shit? Plenty of people get good mileage out of their Tacomas. It's not hard to do, depending how one drives.

 

MI actually raised the speed limits a few years ago. Coincidentally at the same time they raised the gas tax.

Genuine question: other than California and sales, what governments have banned gas vehicles?

 

Yes. I have a coworker who constantly reminds us that trucks in the 70's and 80's could get 24 MPG. But he was also talking about a tiny 4 banger pickup without 4x4.

 

off the top of my head I think France at least, I feel like there were a couple more. My memory may be very bad here but I think ice vehicles were being banned in sales and something about them being banned completely in Paris itself

 

I'm constantly smashing the pedal and drive 80 as traffic allows. I average 20.5 per gallon. I'm running KDMAX Pro. Sliders and Backflip cover, stock wildpeak tires.

 

I remember when Montana lifted the daytime speed limit in the mid nineties...back then I had a VW Jetta GTX...16v...nice car but unreliable. Drove down there (I'm just up across the border in Alberta) to open it up...reached 201 Kilometers per hour!, ended up trading it for a BMW...

 

You traded 1 unreliable car for an even more unreliable one, haha!

 

If i drive easy and set the cruise i can pull 23 to 26 mph but my truck is not 4x4 and i have a camper. And that is on open roads.

 

I generally do 80-85 here and according to the dash I get 20mpg. Stock SR5 4 dr

 

The single biggest drop in fuel economy occurs when speed is increased from 65 to 70 mph (9%). MPG is relatively constant until 55 mph is reached and wind resistance begins to take effect. This is a general calculation based on average cd and frontal area and is not based on a particular vehicle. Yours may be different than this but the premise will be the same.
speed increase from 55mph to 60mph -3%
speed increase from 55mph to 65mph -8%
speed increase from 55mph to 70mph -17%
speed increase from 55mph to 75mph -23%
speed increase from 55mph to 80mph -28%

 

Preach on brother!

 

What your saying is… we need to turbo our tacos…

 

Damn menaces to society

 

I get about that with a dclb