New to me 2011 Prius why is it getting 35-37MPG!!!

Our 2008 Prius normally got between 43 and 50 mpg. We sold it with 163K miles on it. Zero problems except...

For two or three tanks of gas we got in the mid 30's mpg. This was when the car had about 130K miles on it. Of course I thought it was the traction battery but after several tests decided it was good. I determined the problem was with the ICE. On a whim I dumped a can of SeaFoam in the gas tank. The mpg jumped back into the normal 43-50 mpg range. My guess is dirty injectors.

 

2010 Prius with 156K miles, I get 40-41 mpg with AC on full blast for 8 hours in 95+ degree Texas heat.

 

Just to confirm, and this is due to Toyota's insistence on fudging the numbers: is that displayed or calculated?

 

Just did 640 miles yesterday, pulling my camper on the interstate. Cruise control set at 5 mph over speed limit, averaged 43.9. Ac on the entire time. This was in the southern heat too. If your only getting 35 something is wrong.

 

Great news!!

 

149k on my 2010 with 17" FRS wheels get between 47-50

Pixel XL ?

 

Tire pressures may be part of this Gordian Knot: my dealer always put tires back at the 35psi spec after an inspection , but that was with compressed, heated air of course, so by the next morning the tire pressures would be in the low 30s and mpgs were noticeably lower until I pumped them up again.
Since you have significant oil consumption, good luck getting it down.

 

There's nothing ridiculous about low instantaneous gas mileage during acceleration. Any car uses a lot more power to accelerate than to maintain speed. A good running Prius might be some percentage higher, but will be in that range unless you are hypermiling. I see low mpg during acceleration, but that gets averaged out overall, and I'm getting 56 mpg indicated (maybe 54-55 mpg actual) 300 miles into my current gas fill up. 169K miles on the odometer.

 

That is impressive. Have you cleaned out the EGR system, intake manifold, replaced the PCV or any other major maintenance that's not in the official Toyota maintenance schedule?

 

Yes, all maintenance is up to date, including complete EGR system cleaning to like-new condition, which is not in the official Toyota maintenance schedule. Did replace the PCV valve, though it seems OK, though passing a lot of oil and sludge. Have an oil catch can ordered and coming on a slow boat from China. I've been reading Priuschat since before I bought my Prius (to research reliability issues), so I know the potential issues and have taken care of everything mechanical (still need to get around to doing some paint correction).

In doing research on this particular car before I bought it, I learned that at 149K miles, 1,000 miles before I bought the car, the Toyota owner's database shows that the previous owner complained about lack of power and 35 mpg, but the dealer didn't find anything wrong and didn't do anything. When I was trying to buy the car, it failed the smog check due to a check engine light, was taken to the dealer to be fixed (MAF sensor and vacuum purge valve). It then had another check engine light while the previous owner was driving it for a week to clear the readiness codes before taking it back to smog check, and the A/F sensor was replaced to fix that. I still went through with the purchase. Maybe those things brought the mileage back up to around normal from 35 mpg.

Other things: Inverter failed at 128K miles under previous owner (enhanced warranty covered), so it has a new IPM (guts of the inverter) and shouldn't fail again. EGR valve was sticking and was replaced under another enhanced warranty at 158K miles. I did new spark plugs (twice... one was causing a misfire, so I replace them all with the Denso Twin Tip model last month). I have used only Top Tier gas since I learned about that, and have run Techron twice. Burns minimal oil, though I monitor at each gasoline fill up because it is a good practice: about 1/8 of a quart in the past 8k miles. Original 12V battery that is fine even though it drained it twice (leaving doors open for days and similar). It's it tip top shape, and I expect it to go 300K+ miles.

My recent driving has also been pretty ideal for gas mileage. I use Trip Odometer A to monitor daily trips and Trip Odometer B to keep track of current tank. Right now, my driving is mostly slower speeds in town, which helps gas mileage if the trip isn't too short (at least 7 miles or so to potentially get up to the high 50s mpg). If I want to semi-hypermile, I can do a 20 mile round trip with several hours between going out and returning (2 cold starts) and get over 60 mpg (63.7 on dash the other day). Several days ago I did a longer drive that was mostly winding highway (cruise control 55 mph), and then the 7 miles uphill on a low speed gravel road. Round trip for that was 85 mile and 57 mpg on the dash.

 

What's the brake orientation thing?