All, any insight you have would be appreciated. I have a 2004 LS 430 with 220,000 miles on it. Over the last 6 months or so I have noticed that the average mpg that shows on the dashboard indicator has decreased form 19.9 mpg to 19.5 mpg. During that time my driving habits changed. My commute from Plano TX to Fort worth TX (about 120 miles per day ) decreased to about 45 total miles total per day. However even during the shorter commute my average mpg per the computer has decreased from 19.7 to 19.5. The last two decreases curiously seemed to have occurred right after the oil change at the dealership. Tires are in great condition, properly inflated, and oil changed every 5k-6k miles. I recently took it on a long rive to Austin TX and back (3 hours each way - I think) and the average dd not budge from 19.6 mpg

Any thoughts on what might be causing this decrease? Might there be a bigger issue? Or is this a non-issue?

Thanks

 

Personally I wouldn't worry about it, but a change in commute could certainly do something like that. There's lots of factors in a commute...idle time, hills, traffic, etc. If any of those things changed, and I guarantee they did, your mileage will change. Weather/air temp also has a huge roll in it, but the warmer weather should actually help your situation.

There's other things to consider...the oil you got changed, did they use the same weight you've always been using? Even the way you drive, has that changed? Are you trying to get to work faster? I spent a couple months driving faster than I normally would and I noticed it in my average miles per gallon for sure. But if I had to guess I'd say it's your commute. Either way I wouldn't worry about it.

 

Don't feel badly. With 99% city driving I get maybe between 11-12 mpg.

 

The amount of ethanol added to pump gas changes throughout the year. Most places have a summer and winter blend that are different and the amount of energy per gallon varies. I would not be worried about .4 mpg.

 

The LS has its highest gas mileage on long distance, highway speeds with few stops. It is commonly reported that LS owners get around 27 mpg on such trips (I also confirm that). The shorter the distance with increasing stops means the mileage is reduced proportionally. I don't think you have anything to worry about.

 

19.9 -> 19.5 is %2 change
19.7 -> 19.5 is %1 change

Those mileage percentage changes are statistically insignificant.

 

I'm in a similar situation. My tank avg has gone down and my driving habits haven't changed.

I'm thinking of doing the BG44k treatment and cleaning our my MAF in hopes to improve my tank avg. I used to get about 400-425 mpg per tank fill, now it'a about 330-360 mpg.

 

Let me know if you notice any difference. I have always gotten about 330-360 miles per tank. Driving form LA to TX, I htink I might have gotten close to 400.

 

For what it's worth.....Even the older Lincoln Town cars will get over 20 mpg with all highway driving. Personally, I feel that the LS430 ownership is for comfort and superior engineering.

 

Our 2001 has around 198K. It is now my daily driver with a 135 mile round trip commute. When it was the wife's car around town it got 19-20 routinely. Now as my commuter it gets 23-25 and I stretched one tank to 502 miles (with about 1 to 1.5 gallons to go before the fill up).

Cannot complain and hope this holds at these numbers for a while.....

I keep a log book to record mileage and would not trust the displays for accurate information.