Last weekend and this weekend, I came up to the cottage. Normally I get 45+mpg on the highway (220 miles one way, avg speed probably 78mph). Last weekend I noticed I averaged 43.1mpg and now this weekend 40.4mpg. Tires are 44/42. Oil has 2100 miles on it and is the same I always use, full synthetic 5w30. I cleaned the engine air filter a few weeks ago. I cannot come up when any reason I am getting crappy highway mileage all of a sudden- I'm open to suggestions!
I'm guessing it's colder this weekend than last weekend. I went from 57mpg down to 50mpg in 2 days due to colder weather. Time to grill block.
A strong headwind and cool temps will kill your mpg. You won't get it all back with a tailwind. It's been rather windy in SE Michigan the past week. All other things being equal, that's probably it.
+1 Gas formulation might have changed too. And just a couple of MPH difference in average speed can make a big difference too.
You know what I'm wondering .... I might be due for an alignment too, I've never had one at least In the two plus years I've owned it. I have 93500 miles and I installed a Yuasa 12v battery about 6-8 months ago. I can look at my mpgs on fuelly for past, colder trips up to the cabin and I consistently have gotten 44,45, heck once I got 48mpg on the trip here and home! I know members here report lower mpgs right before a problem pops up, I hope I'm not on that path!!
Ah yes the cottage...reminds me when my grandfolks had cottages on Lake Erie. 78 MPH can easily be 42 MPG for my 2006. Yes we are well into winter blend gasoline now so that is maybe 1 MPG drop. And the other cold weather issues add on to that.
It could be the reformulation of the gasoline lately PG32. It has been changed. That is why the price at the pump dropped. Be thankful you are getting the MPG you are, and enjoy the Prius. I know I enjoy ours no matter what MPG we get... Just got back from long "road trip" myself. Had a ball. Check out the post I started last week and updated this morning. Peace, Ron (dorunron)
That is only one factor in what caused lower gas prices.......and not even the biggest one. For the OP: At the mileage you have, I'd be changing plugs, if you haven't already. And there might be other routine maintenance items that have been missed, like a throttle body cleaning just as an example. How about a dose of Techron in the gas ? An alignment might not hurt but I don't favor that unless there is some real evidence that you need to do it.......like uneven or rapid tire wear.
Hmmm. FWIW I never said it was the only reason. Maybe I implied that, maybe not. Viewers discretion is advised. Ron
Changing the spark plugs will definitely be on my list of to-do before I hit 100,000 miles I noticed today on the way home, that my tires were very noisy. I just noticed lately that they are wearing out at a fast rate. I am pretty sure I need an alignment, but is it common or unheard of for tires to get noisier and give worse mpg's as they wear down? On the way home, I averaged 41.9mpg but once I got off of the highway and drove the 30 miles on roads under 50mph to get home, my average is now up to 44.0mpg. I saved all of my pipe insulation from last year, and I am going to block my grille tonight.
In my experience, it is not common at all. Given that information, I think an alignment and suspension inspection is definitely in order. Be careful with that grill blocking stuff. Lacking a temp. gauge, it is hard to tell if the engine is getting too hot or not. AND done wrong, the blocked grill can actually increase drag instead of decreasing it.
+1 for alignment check. I had mine done and did notice the difference. It wasn't that far off to begin with, but the Prius is sensitive to this.
on my 25 mile drive to work with the heater on my mpg dropped to 28. reset the display same route home no heat back to 44. just the cost of being warm and on those frigid 45 degree florida mornings
I have noticed that around 46℉ (8℃) there is a drop in fuel consumption, but for me it is something like 53 MPG (4.4 l/100 km) to 49 MPG (4.8 l/100 km), so I'm going to go out on a limb and say that there is something else at play here. Also, what was the OAT on your homeward journey? Warmer than 46℉, I'll wager.
