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2003 Deville base
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so I owned my DeVille for about 3 years now and I've never been able to get my average miles per gallon above 12. 6 I do only drive city to and from work about 12 miles a day so it does have very low mileage should I be concerned with this gas mileage or is that about normal for never driving it on the highway that much
 

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2003 Deville Base
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4,798 Posts
Never had mileage that low on my 2003. Our trips around town are 2-3 miles, with some trips to another town of 20 miles. Never had anything less than 19
 

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98 DeVille, 97 DeVille d'Elegance
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Keep your foot out of it or that's about what some get all city... Those jack rabbit starts kill the mileage in a N*. We average 21 with about half city driving.
 

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2003 deville
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I've gotten that mpg as well pure city. But after replacing an outer tie rod align and keeping eye on air pressure got around 13-14.
 

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2003 Deville Base
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Re: 2003 cadillac deville mpg

I've gotten that mpg as well pure city. But after replacing an outer tie rod align and keeping eye on air pressure got around 13-14.
tire pressure will effect mileage, but tie rod? alignment?
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
Yup. Excess toe angle means the tire is basically being dragged along at a slight angle.
 

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1991 Cadillac Sedan deVille
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591 Posts
Re: 2003 cadillac deville mpg

Keep your foot out of it or that's about what some get all city... Those jack rabbit starts kill the mileage in a N*. We average 21 with about half city driving.
Jack rabbit starts will kill the mileage of any car, but especially on a vehicles weighing well over 3600 lbs. People seem to forget their driving style affects their mileage the most. Even the most efficient car (engine) will not be as efficient if it's not driven in such a manner, and vise versa - even an inefficient car (engine) can be driven more efficiently.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,439 Posts
Re: 2003 cadillac deville mpg

4,000 pound base Deville, 275 hp 3.11 final drive. 87 octane fuels.

11 - 15 city
17 - 21 near suburban
25 - 28 long highway run

On anything less than a 12 - 15 or so mile drive the engine and transmission never fully warms up. Oil drag is pretty high. Short, cold runs cause the most engine wear and oil additive depletion.

Put an egg on the gas pedal and don't break it. Run 5W-30 recommended oils, maybe synthetic. Run Top Tier fuels. Inflate the tires to 32 psi all around, cold - NEVER adjust tire pressures when warm or hot - the normal pressure rise with temperature increase is factored into the recommended pressures on the door sticker. The maximum inflation pressure molded into the tire sidewall is for your runs at Bonneville Salt Flats only. Use clean air filters and make sure the intake ducting has no leaks in rubber pieces or band clamps. Clean the throttlebody every year or so. Remove excess junk from the trunk.

Study how and why the average fuel mileage readout works like it does - and how long term resets or just "leave it alone" affects perceived mileage. You fill up and reset the average mileage to 0. You immediately get on the Interstate and drive a half hour at 60 mph. Your average mileage ratchets up to 26 mpg. You get off the I and are immediately stuck in heavy traffic jams for a half hour. Gas mileage drops to 0 and your average mpg for that hour is ....... 13 mpg.
 

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2005 CTS/ 2008 DTS/ 2008 STS V8 N*/ 2011 CTS4 ALL W/D Pearl
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so I owned my DeVille for about 3 years now and I've never been able to get my average miles per gallon above 12. 6 I do only drive city to and from work about 12 miles a day so it does have very low mileage should I be concerned with this gas mileage or is that about normal for never driving it on the highway that much
Are you sure that you are not talking 12.6L/km100? I get 12.5-12.9L/km100 in the winter and 11.4-12.4L/km100 in the summer.
 

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2005 Deville
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My 05 Deville base, gets 16-17 mpg with a mix of 30 min/day stop and go city driving and 40 min/day of 40-50 mph suburban driving. That's with judicious use of the throttle. Constant 60mph on the highway nets 28mpg.
 

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Alexandra - 96 SDV Clyde - 15 Silvy
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Re: 2003 cadillac deville mpg

Jack rabbit starts will kill the mileage of any car, but especially on a vehicles weighing well over 3600 lbs. People seem to forget their driving style affects their mileage the most. Even the most efficient car (engine) will not be as efficient if it's not driven in such a manner, and vise versa - even an inefficient car (engine) can be driven more efficiently.
YUP.

Top gear had a Prius go as fast as it could around their test track, and it was followed by a 5 series. I believe they were out there for 5 laps or so. The Prius got 17 mpg, and the BMW got 19.
 
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