2007 prius, hwy 79 mph, 90% hwy, mpg 42: is it normal?

42mpg at 79mph sounds about right to me. If you slow it to 70 you should see a noticeable bump up.

 

Driving faster will reduce ur mpg.

If u haven't already done so......check ur 12v accessory battery if it hasn't been replaced. If its in poor health it can cause reduced mpg.

 

Buy the way, welcome to the forum

 

the slower you go, the better your mpg's. pretty much true in all vehicles.

 

Yep to both of the above.

You will NOT get 50+ mpg going 79 mph and not even at 70 mph, on a Gen 2.

BTW, you might find Car and Driver: The Truth About EPA City / Highway MPG Estimates | PriusChat insightful.

From ConsumerReports.org - Most fuel-efficient cars, you should be able to achieve 50 mpg at 65 mph. Last page of http://www.consumersunion.org/Oct_CR_Fuel_Economy.pdf describes CR's tests vs. the old EPA test.

 

Based on data collected by members here, this is roughly what you can expect.

41 to 43 MPG at 80 MPH
47 to 49 MPG at 70 MPH
55 to 58 MPG at 60 MPH

 

I agree with all of the above. My experiences are similar to uart's.

On a related note, if you ever replace your tires with non-LRR tires expect another 2-4mpg loss!

 

At 55 we get over 50 mpg, over 55 mpg if the road is flat and it's a warm day.

 

Ha! Uart hit the nail on the head.

I like to drive 75-80mph (hey its Metro Detroit, Im just trying to go fast enough so I dont get carjacked) lol.

I went on a 220 mile trip one way last weekend going 74-78mph most of the time. Average mpg= 43.5.

On the way home, I slowed my roll to 70mph = 47.5mpg.

I have my upper grill blocked completely and the lower 80% blocked. Dont know if that makes any difference at highway speeds or not...