[prr]

I took a quick freeway MPG for my Highlander Hybrid 2006 yesterday. I gassed up, then we went out of town, and came back. This morning, I gassed up and was disturbed to see my mileage on the 111 mile two-way trip was only 22.5 MPG. When I did an MPG test earlier this year, I got 26 for pure freeway. I don't know how I got so low--I was driving 60-65 on the freeway, which was most of the trip.

Looking back, I saw two factors that might have contributed, although I'm not sure at all that either one did--which is why I'm posting here.

(1) There were more people in the car. I am estimating about 500 pounds more of people than there has been in the past (our whole family went). EDIT: Actually I went back and checked, and I got a long out of town MPG at 26, with almost as much weight as we had in the car last night, so I no longer think weight was a factor at all.

(2) it was not a flat grade. We drove from our town some 15 miles from an elevation of 3000 to 3800 feet, then went down a steep grade (6-8%) for 20 miles or so, and our final destination was at 1200 feet. Then, we drove back home the same path. Now I was thinking that the uphill drive shouldn't have hurt our MPG, as we coasted down that same stretch going there, but could we be hurt more by an uphill trip on the same path, than helped by a downhill trip down?

Its hard for me to see how either of these factors could have brought the MPG down so much. Even our pure city MPG is 24, and our combined is 25. Granted, most of those other mileage checks are with only myself in the vehicle. I've been gassing up at the same station for most if not all of the fillups the last few months, including the previous 3 fillups, so I don't think there was a discrepancy about which station said I was full at this level vs. another station saying I'm full at that level of gas in the tank. Of course I double checked my math, and my numbers are right.

Normally, my freeway MPG checks are longer, most if not all of a tank. I just limited it to this 111 mile trip because I've only owned this car for a few months, and this is only the second pure freeway MPG that I"ve taken, so I had to make it shorter.

Of course, I'll want to get another MPG estimate for freeway sometime soon, but I don't know if the shorter distance might have had anything to do with this?

I know the maintenance history of teh car. It is in great shape, has been gassed up at Costco most of its life, I've been going there since I bought it, and I did throw in some techron to clean up any deposits a few tankfuls ago, so it really shouldn't be anything mechanical--and even if it was, there was no sign of this up until yesterday, so I don't see that as an issue.

Any thoughts?