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

[nick63]

I have a 2004 Prius with 17,000 miles on it. I live in S. California. My average mpg has generally been around 43-44mpg (I live in the hills). Last week, I had an intermediate service, and after getting the car back, am now running at approx a crappy 36mpg. And that's with new tires and realignment.

So I took the car back today to the service station in Santa Monica and had them run tests and re-check. They found nothing wrong with the car that would explain the sudden drop.

They did say that they checked nine Prius' on the lot and the average on them at the moment was approx 38.5. And that some owners had been recently complaining of a fuel economy drop.

They suggested that the drop was due to one of two things -
1) Air conditioning - which they said can cause a 5mpg drop, except I rarely use it, so it's not that.

2) The summer addition of ethanol in the gasoline which apparently reduces fuel economy in all cars.

So my questions are -

Has anyone else heard of that problem, has anyone else had a sudden drop in fuel economy, and after a service??

thanks

Nick

[IsrAmeriPrius]

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

Has anyone else heard of that problem, has anyone else had a sudden drop in fuel economy, and after a service??[/b]

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

[john1701a]

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

that's with new tires[/b]

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).

[mgmb]

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

[nick63]

[quote]

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

Huh. I've never heard of that. Really? Why is that?



<div class='quotetop'>QUOTE(IsrAmeriPrius @ May 24 2006, 07:58 PM) [snapback]260746[/snapback]</div>

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

No. What is the significance of the viscosity? Would it not be all the same at a Toyota service center?

[john1701a]

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.

[nick63]

<div class='quotetop'>QUOTE(john1701a @ May 24 2006, 09:01 PM) [snapback]260764[/snapback]</div>

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.
[/b]

Very interesting that new tires could be a negative influence on fuel economy, but could that account for a such an abruptly precipitous drop from 44 to 36 mpg?

And do you know anything about the ethanol mixture in the summer stock of fuel affecting fuel economy for the worse?

thanks.

[tomdeimos]

Ethanol fuel costs me about 3 mpg.

[hycamguy07]

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

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...

[Tadashi]

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.