Gas mileage decline since purchase!

[ml30306]

I own a 2004 Lexus ES330, ca. 120,200 miles now. I purchased the car about 3 years ago, after filling up I used to get a distance of about 280-290 miles on the dashboard display. For the last year it has declined, it now shows about 230-240 miles. Why ist that? How accurate is the electronic display calculation?

As part of regular maintenance I have now done the following (all DIY):

- New spark plugs
- New PCV valve
- Cleaned throttle body
- New air filter

- Cleaned MAF sensor

Any other recommendations to improve the gas mileage?

[pj8708]

Hi Martin,

It looks like you've done much of the usual recommended maintenance.  I'm like you in that I wonder just how accurate the monitor read outs are. But one thing I  have come across once and a while, is the condition of the catalytic converters. Some folks have had their CATs become packed to the point it's a wonder they don't catch on fire. I real'y don't have a magic answer for you but other members will chime in with some more information.

Outside of the car world, you usually find that as things age they are not as help full as they were when they were new. For example, how well does your Fondue pot work? LOL

Paul

[ml30306]

Thanks. I read that the on board monitor seems to store data over given periods and then will calculate the gas mileage average. I do not drive much on the highway, so I assume that when I fill-up it takes my "poor" gas mileage on non-highway roads into consideration. The maintenance I did was needed, the plugs were already pretty burned down and replacing a PVC valve never hurts and is easy to.