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DTS MPG


98deville

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Eversince I bought my 2003 dts it seems to waste alot of gas...more than my 98 deville..I can go to austin (which is 35 to 40 miles there and the same coming back) on a full tank of gas and have about a half a tank of gas when i get back...could it be that it has more power than the 98 so it uses alot more gas...or is there something wrong? I can get close to 300 miles on a full tank of gas. Does this sound good?

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Half a tank on 80 miles seems a bit steep. I have a STS and can get about 300 miles on a tank. Check your mileage through your DIC (average MPG) and report back on your mileage. I'm interested in seeing what your coputer says you are getting for mileage.

-Dusty-

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Half a tank on 80 miles seems a bit steep. I have a STS and can get about 300 miles on a tank. Check your mileage through your DIC (average MPG) and report back on your mileage. I'm interested in seeing what your coputer says you are getting for mileage.

will do

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I checked the average MPG on my DIC and the number jumps around it went from 14 to 15 to 55 then back down to 14 MPG. On a full tank of gas the dts gets 285 miles, thats driving in town and on the highway very little..How come it's getting poor mileage ...my 98 deville d'elegance can get close to 400 miles on a full tank

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I checked the average MPG on my DIC and the number jumps around it went from 14 to 15 to 55 then back down to 14 MPG. On a full tank of gas the dts gets 285 miles, thats driving in town and on the highway very little..How come it's getting poor mileage ...my 98 deville d'elegance can get close to 400 miles on a full tank

Does the 98 have a much larger gas tank?

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I checked the average MPG on my DIC and the number jumps around it went from 14 to 15 to 55 then back down to 14 MPG.

That sounds like you are displaying instantaneous MPG instead of average MPG.

And the overall fuel economy sounds like a leaking fuel injector or leaking fuel pressure regulator or some other leak in the fuel plumbing that is dumping fuel somewhere other than in the engine.

If the leak is external to the engine, you should be able to smell fuel vapors.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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  • 1 month later...

I just recently noticed that when accelerating the RPM's go up real high around 4000rpms and that just accelerating to 40mph. Is this normal, should the rpm's be going that high under normal acceleration...thats probly where all the gas goes...

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I checked the average MPG on my DIC and the number jumps around it went from 14 to 15 to 55 then back down to 14 MPG. On a full tank of gas the dts gets 285 miles, thats driving in town and on the highway very little..How come it's getting poor mileage ...my 98 deville d'elegance can get close to 400 miles on a full tank

Does the 98 have a much larger gas tank?

They both have the same size gas tanks if I'm not mistaken

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As a point of comparison, my base model 2000 Deville gets between 18 and 19 MPG (right now the DIC shows 18.1 MPG average). That's a mix of highway and city driving. If I zero out the average MPG reading at the start of a trip, I'll get a little over 19 MPG for highway driving. My owner's manual says the fuel tank holds 18.5 gallons but I get the "Low Fuel" warning after using about 15.5 gallons. I rarely let it go past 16.5 gallons used. I generally get just under 300 miles per tank of gas.

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I wonder if the catalytic converter could be plugged. Does the car lack power?

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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On my 04 DTS I get 19.4, mostly freeway. This is very close to my 93 STS which gets 19.6 average.

The DTS is about 180 lbs. heavier, which is negligible.

-George

Drive'em like you own 'em. - ....................04 DTS............................

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  • 3 weeks later...
on the display it said 16.5 MPG Avg.

The point is, Avg mpg should not "jump around" It should be a relatively stable reading since it is an average.

I will say that some computer programs have change recently, and I'm not sure that Cadillac has ever adopted the newer version. I say newer because there is a HUGE difference in the way my 2007 Dodge Ram calculates "average" when compared to my '99 STS. The Dodge seems to start the new average using the CURRENT average as the starting number. My '99 STS started the calculations using the current INSTANTANEOUS mileage as the starting point. A very big difference in reality.

In either case though, only the instantaneous MPG indicator "jumps around" very much.

SO, when you are driving on the highway at a steady speed, cruise control ON, and you reset the instantaneous mpg reading, what do you get as a result? Doing that on my 99 tells me I'm getting about 27.5 mpg........straight and level road, 70 MPH.

Never underestimate the amount of a persons greed.

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