Sudden Drop in Fuel Economy After Service - Ethanol additive in fuel?????

All the gas stations near me are adding ethanol now. Does the type of gas make a difference? BP is pushing their "invigorate" but I notice its not a "Top Tier" company. Others swear by Mobile. any opinions?

 

Same thing here with the Tire Pressure. I got my Prius serviced and left for a long trip. I noticed that the ride was a little softer. I then realized what had happened. My mileage had also dropped the 3mpg.

 

The HydroEdge tires from Michelin were loud enough to resemble the sound of snow tires. Now that they have been replaced with other tires, the noise level has dropped and the mileage has gone up somewhat near to normal for my driving: 44-46 average per tank of gas.

 

I am interested in tire pressures. My 2008 came with 37# in the tires. Can you safely run 42# & how much would that affect mpg? This winter my mileage has gone from 45-46 to 33-35. The cold weather has probably lowered the pressures but not enough for the warning light to illuminate. Does it ride ok with 42#? Thanks a lot. I got my car last April & love it. It's surprisingly good in snow.

 

You have two questions I'll answer: Is 42 safe? and, How does it ride?

It is quite safe, and it could be argued, safer than 37. 37 isn't by itself unsafe, of course. But 42 gives you a little more margin of error for reductions in pressures from things like slow leaks or ... cold weather. Which makes a great opportunity to emphasize the importance of regular tire pressure checks, especially as the weather cools. Anyway, many in these parts run 44 in the front (the max cold inflation pressure for the Goodyear Integrity) and 42 in the rear. (The 2# offset is to adjust for the heavier load in the front end.) Though not recommended, some even run them higher, being very confident in a substantial margin of safety on the high side.

As for ride, you might notice it to be a wee bit harder.

So it's a personal choice: better fuel economy or possibly a slightly better ride.

 

I have a 2006 Prius. Had been getting ~ 47-54 mpg, last 6 months has gradually declined to a poor 37 mpg. Taking it in to Toyota today!

 

Mr

We have 2 Prius's- a 2006 & a 2008. 1) About a week ago I noticed a drop in MPG on BOTH of them. We live in S. FL & use the A/C all year round. It does not take off 5 MPG, perhaps 2-3. 2) I bought new tires for the '06 last year and the MPG dropped by 3-4 MPG. After 5K miles it picked up a little, but I was told that the stock Goodyear's that I bought have a different compound than the Jap Goodyear's from the factory.

3) I am a mechanic and I know what caused the hit to both cars- It's springtime & the refineries are changing the gas per the EPA. I get my gas @ the same place- (Sam's Club) all the time. There are no other variables that I am aware of. We were getting around 48 MPG with the 2008- it has 7K miles on it, and around 50 MPG with the 2006. Almost all of our driving is in city and here the land is very flat.

Hope this helps. Walker

 

Mr

I run my fronts @ 42 and the rears at 40 lbs. Many Prius owners run this tire pressure. No, it won't hurt the tires or the car.

 

Mr

Our cars are VERY sensitive, especially with tire choice. I just stick with the stock tires as they work best for my type of driving & area.

On a side note: My Harley motorcycle has a 1200 CC engine. It always gets 50 MPG no matter how I ride it. I attribute this to a high horse power engine that does not work very hard unlike our Prius's. They are quite touchy in the MPG dept.

I also use full syn. oil which may help the milege a little as it's more slippery than non syn. oil. Hope this helps.

 

When did you last check the tire pressures, and what were they?

"The dealer does it" = BZZT! Wrong answer. Tire pressures should be checked at least monthly. Six months is plenty of time for changes in average outdoor temp and/or slow normal leaks to lower the pressures and thus MPGs significantly. (And, if you have been using 42/40 psi front/rear to improve MPGs, dealer techs will very often lower the pressures to the factory settings.)

 

As I've seen mentioned in other threads, overfilling the engine oil will cause a significant drop in mpg. It should not be above the "full" line, from what I understand

 

To All: I upped the tire pressure to 44 lbs. front & 42 lbs. rear tires with NO difference in handling. I live in a very flat area. I will post on any milege change on both Prius's.

 

I hate that they add ethanol to gas!!!
It certainly does affect mpg.

:ban:

 

A/C does have a significant impact on fuel economy, due to it's drain on the battery (very strong), and the engine having to run much longer to keep it all charged up. Mine drops significantly with a/c (or defrost, for that matter). Ethanol 10% will have an effect, roughly 5-10% drop.
Mike