Cadillac: Poor Fuel Economy, poor fuel economy, fuel mileage

Question
I have a 89 eldo with a 4.5L, which I bought about 4 months ago, 77,000 miles, runs excellent but it doesn't get the same MPG as my 88 deville with 173,000 miles and the same 4.5L.  I noticed that when on the highway and I take my foot off the pedal, the instant MPG goes to 70mpg on tht deville and on another caddy that I have... but on the eldo it will only go to 55-60mpg... I get 25-26 mpg with the deville on long trips and only about 21-22mpg with this new eldo.  any thought on what might be doing this and how to improve the MPG so that it will be the same as my deville?

thanks


Answer
NEVER rely on the INSTANT MPG display as they are simply for SHOW and NOT accurate. People like to see things flashing and lights blinking so the manufacturer adds these units. In my professional opinion as selling points.

Perform an actual basic fuel mileage test as you would normally do with a 20 year old vehicle by filling the gas tank, Drive a hundred miles or so and refill the gas tank and compute the fuel mileage.


Let me know.


autohelp