How accurate is fuel monitor

Super high tire pressure in the upper 40 psi range and low rolling resistance tires might resolve that... Also hybrid battery reconditioning could help too: FAQ

 

you bought an 8 year old car that may need work, or is is just plum worn out

keep an eye on the oil, and clean the egr

 

@CWM How many miles on it?

Something easy you could try first: add a fuel injector cleaner with the next fill up, the proscribed amount, something with PEA (PolyEtherAmine).

Best Fuel Injector Cleaner – Review & Buying Guide in 2018

 

According to some recent info I saw the average age of a vehicle on the road in the US is 11.2 years... So if you're telling 'em that a vehicle 3 years younger than the average is worn out I question your upper class privilege.

Sure would be nice if people on PriusChat who have enough money to afford a new or newer car weren't allowed to advise us poor folks on what they think of our vehicle buying, owning and repairing decisions.

We're doing the best we can with what we got and rather than "helping" us maybe you should instead focus on the other Prius forums where snooty new Prius owners with never-ending upside down car financing packages ask endless questions about what floor mats they should buy and how to polish out a scratch on their precious new car.

 

you're losing it man

 

Yea... Why don't you try only having $30 in your bank account and see how well you keep it together... Oh yea, I forgot, you don't care, you got your expensive car and money in the bank, why care about the majority of the people you're surrounded by? The stench of wealth and privilege is one of the worst smells there is.

Majority of Americans don't have $500 in savings

 

The list of what could be causing poor fuel mileage is endless when we know nothing about the car except it's an 8 year old car that was purchased 2 months ago.

Your report of 45 MPG is about what one might expect, while your reported readings of 5 to 10 MPG and the report of 90 to 100 MPG may be due to the display that has gone south.

 

2010 Prius: I discussed this with my dealer. He indicated he gets this question about this time of year.
I get about 50-51 on true regular gas in the summer season. I pay about 10% extra to put true regular gas in my 2010 Prius when I can find it.. MPG can drop in the winter season as low at 45-46. In my area Ethanol 10% blend is almost the area's most standard regular gas. IMO that does reduce the MPG in a negative way dropping often below 50. My dealer also says the oil companies modify the regular gas formula seasonally to make heating oil for homes without consideration of Ethanol. That too is a factor in MPG. I have had winters when I was down to 45-46 for much of the season.
I agree the on board display indicator for average driving speed is often a joke. I have driven most of a tank of gas on the interstate after some city driving and it seldom rises above 32 even on a long trip. To be fair, when I gas up and hit the interstate, it is capable of displaying 50+ until I get into lesser speeds (two lane roads and city driving) when that number drops significantly..
IMO, my sister drives more aggressively in her 2010 Prius and the MPG displays abut 44-45 everywhere she goes.

 

I'd submit that air temperature is causing most of that MPG decline, not so much winter fuel. I can get 53 MPG when temps are 75 to 85 degrees, but drop back to lower 40's in winter when it's near freezing.

 

Except my remarks hold true even in modest temps - mid 50s - mid 60s. in the calendar winter months.

 

Winter conditions are made even worse, if you're parking outside, need to run the car to defrost windshield. And worse still if it's mostly short trips: all the harder to recoup the time spent idling.

Things you can do: get the car into a garage, use a block heater, and try to consolidate trips, as much as practical.

 

I had a 11 Prius bought new, for three years. Live in SoCal, averaged 44mpg lifetime, which was the same as Consumer Reports. No hyper miler, trying that in LA could get you shot.