Hi all - One year old Prius with 15k miles - Started last June with 55 on road and 44 around town. Settled in at about 42 to 44 most tanks. Four tanks ago got 38, then 40, then 42, now this tank back to 36.xx. Taking it in tomorrow morning to see what Toyota will do! When I first got it you really noticed the CVT "gearing down" to lower the engine RPM. Not nearly as noticable now so it'll be interesting to see what Toyota says. They're bragging in their new commercial here in Ca about 52 MPG by owners. Anyone out there have a simular problem - All the owners I talk to say between 44 and 55 mpg. Last trip 1000k all freeway netted me 42!!! at 73mph. Others I talked to at rest stops were saying 55 at 75mph. Help!! Bill

 

A Prius doesn't get 55mpg at 75mph, 42-45mpg is more like it, assuming it is driven somewhat normally and depending on headwinds. At that speed, if you had some headwinds, combined with A/C use, that would be about right, based on my experience.

 

What is your tire pressure at? Are there alot of hills in your commute? Do you have alot of lights in your commute?

Also, as mentioned above, I wouldn't expect to get 55mpg going 73mph.... high 40's or low 50's at best.

 

I agree with John: 55 MPG at 75 MPH won't be sustained under typical driving conditions. Maybe under limited circumstances for a limited time, such as with a good tail wind (see below).

42 MPG is within normal limits for 73 MPH. The Prius MPG Simulator calculates fuel mileage to be 44.23 MPG at that speed, assuming absolute steady speed on level terrain, 75F, no wind, climate control in use, 325# load (occupants and cargo), OEM tires inflated to 38 front & 36 rear. Add in the inevitable accelerations and decelerations, climb some hills, throw in some head or cross winds, drop your tire pressure a few PSI, or carry a passenger or more cargo, and it will be lower. On the other hand, a 15 MPH tail wind boosts it to 55.89 MPG.

I "brag" about my current tank of 68 MPG, but it's not at highway speeds; it's all around town and with careful attention to my route, driver-controllable vehicle variables (e.g., tire pressure), and driving technique.

 

Hi Bill,

You are doing it right, given the age of the car, let Toyota 'do their magic' first to make sure everything is OK. When it gets back, you might take the FAQ and just go down the list to see where your car is. But let's wait until Toyota gives the car a 'clean bill.'

Now as for expected performance on the highway at 73 mph:


In my older, 2003 Prius, I would expect 49 MPG@70 mph and 39 MPG@75 mph without the AC. Your "42 MPG" is in the middle and not all that bad, considering the speed. Now if you could throttle back to between 65-70 mph, you should see better than 50 MPG.

Bob Wilson

 

Like other folks have said;55mpg at 75 mph is an outright lie(or downhill or with a 15 mph tailwind).
What sort of gas are you using; if you switched(or the gas station switched) to 10% ethanol,you would lose about 3-4% mpg-about 2 mpg.This isn't quite you 4 mpg loss, but ballpark.
What color is your Prius? If your Prius is black,and you are a heavy ac user, it might cost you a bit, but usually short trip winter mpg is 2-4 worse than short trip full ac summer mpg.
Luck,
Charlie

 

Thanks for all the input. I tend to believe people when they tell me their mileage. Lets forget the 55mpg at 73 - I got 42 for the trip back which was finished with about 40 miles at 99mpg (down Cajon Pass in San Bernadino Ca). My real concern is from one tank at my "normal" 42-43 to the very next tank at 36-37!!!! Same conditions, driving same places, same times, same speeds, etc etc. Only difference is it's been about 7 degrees warmer 100 vs 93. Last and first time this happened it went to 39mpg for the tank. this one is on tract for 36.3mpg - Didn't get into dealer today, probably next Tuesday. Have any of you experienced any sudden drops in MPG like this? If so what happen? Thanks Bill. PS last summer during simular temperatures I was getting 44!!

 

Once when I took the car in for service and they let the tire pressure down after removing my pressure sensor caps. I had to go back and pickup my special tire caps and the 'supervisor' called them "batteries." After buying the car and finding an extra quart of oil, I don't give maintenance folks a chance any more.

Bob Wilson

 

We came back last month from a 1500 mile round trip to NC all highway. We got 48.8 going down and 50.2 coming back with the cruise set at about 71-72. Temp was anywhere from 80 to 90. The is summer I have been averaging about 56 mpg but that is going at about 55 or so with no cruise.

 

Tank to tank mileage can vary substantially due to the bladder type gas tank. Try filling up at the same station and pump and the same time of day. This will smooth out the variance some.