Well took our Gen1 on a 180 mike trip one way and only achieved 44mpg highway I know they are city machines and this one has proven over 55mpg on a city tank... Has anyone ever tried any aero mods to further the highway mpg?
Why are you expecting so much more? Per Compare Side-by-Side, the Gen 1 (after adjustment is EPA rated at only 41 mpg highway). Read Car and Driver: The Truth About EPA City / Highway MPG Estimates | PriusChat to learn more about the EPA tests.
Check tires are inflated to 40 psi at least (check their max inflation rating) and then you don't mention if it was windy, flat terrain, were you going over 65 mph? Anyways, 44mpg isn't that unusual.
I've never gotten any better than mid-40s on the highway (unless it's a constant crawl that pins the mileage meter) or high 30s in town. That's normal driving, without annoying every driver around me by coasting all the time, but this mileage has held even with a new battery pack and close to 50 PSI tires (courtesy of a Prius specialty mechanic).
On level, no wind, 70F days, setting the cruise control for 65 mph has always returned 52 MPG. But then I've done a 4-wheel alignment too. If I were getting 44 MPG, I would assume I'm running speeds slightly over 70 mph. Bob Wilson
There's also the question about the mileage in the other direction. Who knows what the wind was like and whether there was a net elevation gain? OP can use Google Earth can give you an elevation profile of a route between 2 points! | PriusChat.
I will add that even if you have tires inflated to say 45 PSI, outside temperature will also play a role...I drove across the Southwest last month and outside temperatures in the triple digits helped me get even better MPG...but it was 117 or so outside...
Did you use your a/c by chance? If you drove in town with it on, it will suck your mpg down rather quickly! Back in July we had a week of triple digits, while I was sweating my rear off with no ac, I achieved 54mpg over 150ish miles. My wife drove the car 4 days and returned it with a mpg average of 37.4 and added 120miles on it. I almost had heart failure.. lol Since that incident, I have played around with using the ac at highway speeds, Maybe it is just my driving style, I do not know, but with the ac on, I typically lose roughly 5-8mpg compared to driving the same road in same conditions etc with the ac off and the windows down.
Tires all at 40 cruising speed at 68 seems that should have been the sweet spot this style motor...we did have a full load and temps only in the 50's and 60's so no ac . 2 peeps 2 dogs and a weekend of camping gear lol I guess I should be happy! It also has 4 new tires and a 4 wheel alignment ....did find it really needs struts for the back roads lol Have fun ! Eric
Check the calibration of your odometer against know sources: GPS or highway mile markers. It is common to find tires are off. The stock tires are 902 revolutions per mile. I'm using deliberately oversized, front tires, to improve steering stability but the car now reports 6% shorter distance, MPG and mph. So I apply a calibration when recording mileage and use a GPS speedometer. For example, at 47 mph indicated I'm running a true speed of 50 mph. Bob Wilson
