Mpg from 47 to 40

briand · 10-12-2009, 11:07 AM

This past weekend we took a trip from Charlotte to Atlanta. My Prius is a 2004 with 108,000 miles on it. I normally get 47 mpg but on this trip I averaged 39-40 mpg. Since its fall and the A/C is running I should have got slightly better than average mpg. My tires or tire psi haven't changed.
What could cause this drop in average?
I have looked through the schedule maintenance book and there is no major service until 150,000 mi which is spark plugs and coolant. So what gives?

usbseawolf2000 · 10-12-2009, 12:10 PM

I remember the spark plugs and coolant are actually at 110-120k miles. Have you changed the engine air filter at 90k?

briand · 10-12-2009, 01:09 PM

Yes, I changed it at the last oil change.

alfon · 10-13-2009, 11:53 AM

Quote:

Originally Posted by briand

This past weekend we took a trip from Charlotte to Atlanta. My Prius is a 2004 with 108,000 miles on it. I normally get 47 mpg but on this trip I averaged 39-40 mpg. Since its fall and the A/C is running I should have got slightly better than average mpg. My tires or tire psi haven't changed.
What could cause this drop in average?
I have looked through the schedule maintenance book and there is no major service until 150,000 mi which is spark plugs and coolant. So what gives?

Maybe your state has switched over to Ethanol gasoline which contain 10% ethanol. This will decrease your MPG up to 10%.

alfon

txtabby · 10-13-2009, 06:44 PM

AGH! That's my problem. I can barely get it up to 47, and still trying for 48 on this tank. I'll start using 'better' gas (Exxon, Shell, Chevron, ect.) and see what happens. I talked to a mechanic at the dealership and he told me about the ethanol. Is there anything that can make the mileage get back up to 48-50+?? Going to make sure the air filter is always clean too.

10-12-2009, 11:07 AM	#1
briand Junior Member Join Date: Aug 2008 Location: Charlotte, nc Posts: 13 My Car: 2004 Prius Model: Package: #3 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Mpg from 47 to 40 This past weekend we took a trip from Charlotte to Atlanta. My Prius is a 2004 with 108,000 miles on it. I normally get 47 mpg but on this trip I averaged 39-40 mpg. Since its fall and the A/C is running I should have got slightly better than average mpg. My tires or tire psi haven't changed. What could cause this drop in average? I have looked through the schedule maintenance book and there is no major service until 150,000 mi which is spark plugs and coolant. So what gives?

10-12-2009, 12:10 PM	#2
usbseawolf2000 HSD PhD Join Date: Sep 2004 Location: Queens, NY Posts: 3,254 My Car: 2006 Prius Model: Package: #3 Thanks: 106 Thanked 178 Times in 111 Posts Friends: 59	Re: Mpg from 47 to 40 I remember the spark plugs and coolant are actually at 110-120k miles. Have you changed the engine air filter at 90k?

10-12-2009, 01:09 PM	#3
briand Junior Member Join Date: Aug 2008 Location: Charlotte, nc Posts: 13 My Car: 2004 Prius Model: Package: #3 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Re: Mpg from 47 to 40 Yes, I changed it at the last oil change.

10-13-2009, 06:44 PM	#5
txtabby Member Join Date: Mar 2007 Posts: 37 My Car: 2007 Prius Model: Package: #5 Touring Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Re: Mpg from 47 to 40 AGH! That's my problem. I can barely get it up to 47, and still trying for 48 on this tank. I'll start using 'better' gas (Exxon, Shell, Chevron, ect.) and see what happens. I talked to a mechanic at the dealership and he told me about the ethanol. Is there anything that can make the mileage get back up to 48-50+?? Going to make sure the air filter is always clean too.