What is mpg at 78-80 mph?

You are forgetting the .25 Cx of the Prius... it beats the Corolla hands down at any speed.

Any inefficiencies of the HSD at highway speeds are compensated by the car with the lowest Cx in the world (production).

I don't know what is the Corolla's Cx, but it has to be over .30 which automatically means a heavy penalty over the Prius.

I definitely do over 40 mpg at 75-80 and could do better if there is no traffic as I have to accelerate more often that I want to due to tortoises on the left lane...

 

I usually try to stay under 75 (set the cruise to 72) but today I thought I pick up the pace (especially since gas prices are down) to 82 mph, for a mile or two, instantaneous was only reading about 27-31 mpg. According to charts the gen 2 should get about 24 mpg at top speed.

From posts around here say it should be getting high 30s low 40's @ 80 mph .hmm?
Got ecopias with 42/40 psi.
Should I be concerned?

 

Instantaneous takes into account temperature, cross-winds, terrain/elevation differences, road surface quality, etc. I get less than 15mpg instantaneous driving up our hill for 2 miles. But on average it all works out.

 

Less.

 

Life time average in Buffalo NY driving 71 mph is 44 mpg. I slow down a little for ice.

 

That seems pretty realistic, I feel like my car should get about the same. Sadly cold weather takes down the mpg's. It's in the 20's right now in TN

 

Lol @ 20 being "cold"

 

That's shirt-sleeve weather around here this time of year.

 

Hey now! I swear it's always felt colder in Tennessee then all the places I've been up north somtimes because we get such humid cold weather here. The weather here is retarded sometimes. One Christmas I was in Colorado walking in the snow with a t-shirt on, it was great! Lol

 

this isnt scientific but at 79mph on so cal freeways av says 44-46mpgs. speedo off 2mph and i believe display off about 2mpg. cold here in socal this year is mid 40s so far. you guys are tough