At what speed does the HHR start to get poor mileage?
 

My mom used to have my HHR and she said she often got more than 30 MPG on the highway. She lives in an area of Arkansas where the maximum speed limit is 55, and I live in an area of Oklahoma with 75 MPH turnpikes. I've noticed that if I keep it at 65 or below that I get good gas mileage but if I get over 70 then it seems to drop quite dramatically. At what speed does your car get optimal mileage?

Moved your post from the GENERAL forum into a more appropriate section -

Over 65 mine drops fast, 55 optimal by a bit.

sorry

I find 55-60 to be optimal for both MPG and cooling. My coolant temp gets the lowest when cruising at about 58 MPH (Yes I watch my coolant temp during my hour long commute. Gets boring!!!! )

Mine at 60-65 would get in the mid to upper 30's without AC. Once you past 70, and especially 75 upper 20's, maybe 30.

Same as I have experienced. Sounds like all of these trucklets are about the same.

It's got little to do with make/model of car...typically about 60 is the fastest you can go before you start experiencing a rapid fall off in MPG. It's a product of parasitic drag, so the more "stuff" you got sticking off your vehicle, or the less aerodynamic your body style is, the lower that speed will be.
When I was driving semi long haul, 55 would give the best MPG, but who's gonna go that slow..??..I settled for 65 and paid for the extra fuel. Incidentally, when I started driving I'd spend about $25,000 to $30,000 a year on fuel...my last couple years of long haul that had gone to well over $100,000 a year, I think the last year was $118,000.00

It has everything to do with make/model of car, at least, in this instance.
Title of thread:
At what speed does the HHR start to get poor mileage?

the higher the engine speed, the greater the consumption of gasoline. The engine speed is falling sharply during the next gear change (arrow goes down), but the crackdown continues. Keep an eye on the tachometer. Thus you can find the best option for any tempo driving.
I do remember my upper stage - 87km / h or 53 miles / h. Previous I do not remember unfortunately.
I must say, the upper level creates some conflict between me and the traffic police. We have a speed limit in the city 36 Miles / h, exceeding more than 48 miles / h - reason for the fine.