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

<div class='quotetop'>QUOTE(nick63 @ May 24 2006, 08:48 PM) [snapback]260736[/snapback]</div>

Nothing this drastic. Did you check the viscosity of the oil that they put in the crankcase and the oil level?

 

<div class='quotetop'>QUOTE(nick63 @ May 24 2006, 10:48 PM) [snapback]260736[/snapback]</div>

Until they wear down a little, MPG will be lower. I've witnessed that effect several times now.

Low pressure in the tires has a noticeable MPG influence too.

As for ethanol, my lifetime average is 48.5 MPG using a 10% ethanol blend all 54,000 miles (2.5 years).

 

I just had my 5K service done on my 2006 and have noticed that my mpg has also drop alittle from 45 to 43.

 

The tiny edges of tread on new tires, which add up to a surprising amount of gripping area, are very sharp.

Take a good look (extreme close-up photo would be great) at them now, then 1000 miles later. You'll notice a correlation between the tiny wear and the MPG improvement.

 

Ethanol fuel costs me about 3 mpg.

 

1) Air conditioning - which they said can cause a 5mpg drop, except I rarely use it, so it's not that.

:huh: The A/C isnt connected to the motor its electric... I could see this on a standard A/C unit on a non-hybrid vehicle...

The mileage drop wouldnt be that much on a Hybrid...

 

Check your tire pressure. The same thing happened to me and I found out they reduced my tire pressure from 42 psi to 35 psi. This cost me about 8 mpg. Once I put it back up everything was back to normal. I now tell them nto to mess with the tire pressure.

 

Ethanol contains less energy per gallon than gasoline, but I don't see how going from no ethanol to about 10% would produce that big of a drop. Something else is in play here. Even if ethanol contained zero energy content, a 10% ethanol concentration would only account for roughly half the drop.

<div class='quotetop'>QUOTE(nick63 @ May 25 2006, 12:06 AM) [snapback]260765[/snapback]</div>

 

<div class='quotetop'>QUOTE(nick63 @ May 25 2006, 11:21 AM) [snapback]260915[/snapback]</div>

It's completely safe for the original tires (Goodyear Integras), which are rated at 44 PSI. (Tire pressure is checked "cold", which means that the car has not been driven more than one mile in the past hour.) Lower pressures are a compromise between fuel economy, handling, and ride. I've used 42/40 for two years with no trouble. The ride is harsher and the handling is different, so if you do try higher pressures pay attention.

 

<div class='quotetop'>QUOTE(richard schumacher @ Jun 8 2006, 07:13 AM) [snapback]267871[/snapback]</div>

I had a similar experience with my first Toyota service at 5000 miles - mileage dropping. Interesting thing was that although my MFD mileage dropped, my mileage based on miles/gallons stayed essentially unchanged. I attribute this to three things. 1. Toyota updated my computer's programming without telling me. 2. They rotated my tires causing differing wear which was more apparent in the instantaneous mileage than the final tank mileage. 3. They lowered my tire pressure from 42 to 32 psi.
Out of all of these, the only one I'm annoyed about was the computer upgrade, really. I understand that they are required by Toyota to set tire pressure to "specs." I have an air compressor at home, so I quickly remedied that problem. I recommend re-pressurizing your tires, and then waiting it out to see what happens. Temperature changes affect this car more than any other, and that may also have its pound of flesh, even though you don't recognize it right off. If no A/C, then are you driving with the windows down more than before? That'll affect things. Have you done more driving in hilly areas recently? Just some thoughts.

--Chris

 

I just had four new tires put on my Prius (Michelin Hydro Edge) and the MPG dropped by 20%! Previous MPG average per tank was 45. The new average 36. AND the road noise was similar to running snow tires! Awful tires. Dealer replaced them at no charge with something else by Michelin and the noise is back to normal levels but the milage is still less than old tires (which were Michelin Harmony). Any thoughts? Anyone?

 

oh...the tire dealer did a minor 70k service while he was changing the tires. I think it was an oil change, air filter and some fluid checks. He swears it wasn't caused by anything he did.

 

I have experienced the same dramatic loss of mileage from 45-50 mpg to 35-40 mpg. Please read the thread I started entitled, "After Service Issues". It gives details of my experience all the way to Toyota's corporate reply to me. I would be happy to answer any questions I can, although I'm still searching for answers myself.

 

tires give worse mpg during break-in. different types of tires have different rolling resistance. lots of factors. give it a couple thousand miles.

 

I'm on my second set of HydroEdge tires now. Going from factory-to-them and from the same old-to-new didn't have any more than the usual break-in. 48 MPG remains my average. Mine are not noisy either.

I bet they sold you an incorrect/larger size. PSI really low in one or more tires would have a big impact too.

.

 

Florida started adding Ethonal (up to 10%) a couple of months ago and my mileage dropped from 52mpg to 46mpg. It was an immediate drop in mileage so I'm positive it was the Ethanol that caused it. I also got verification from several other Prius owners in the area that there mileage was also suffering.