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2011 Crown Vic LX, 2009 Chevy Malibu 2LT
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Discussion Starter #1 (Edited)
I just got back from a 300 mile trip home from vacation yesterday. I was rolling down my exit from I-94 with a smile on my face as I read "28.6 MPG AVG" on my 1995 Deville 4.9's display. I traveled anywhere between 65 and 80 mph the whole way. This is a record best for this car and it occured at a hair over 170,000 miles (turned over 170k on the trip).

What's your 4.x powered cars personal best?
 

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1998 Seville STS / 2013 Chevrolet Impala
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1,889 Posts
My 4.9 in my '93 Daily driver got 33mpg average on one trip. Probably because it has a crack in the exhaust that allows about 70% of it to leak out before the cat converter.
 

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'87 SDV
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1,296 Posts
Wow! Those are incredible numbers. My 4100's best was on a cool summer day last year - not using the air on a 200 mile trip, 25.1 MPG. Still beats most crackerbox Hondas!
 

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93 & 88 Allante, 88 Eldorado
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778 Posts
28 mpg on my 88 Eldorado
24 mpg on 93 Allante N* engine
31 mpg on diesel 6.2 Suburban
38 mpg on rented Chevy Impala
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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1,673 Posts
After a recent COMPLETE tuneup on my 1995 Sedan Deville i took a 110 mile trip and really averaged 32.5 mpg on the entire trip! Keep in mind i was the only person in the car with no extra weight such as luggage etc.Also,the winds were very calm the entire trip and i had the cruise control on
---i guarantee if a headwind was blowing at me and i had some people along for the trip,the mpg would be lower for sure.

That being said,32.5 mpg on a 4000 lb Caddy is excellent!

I have made the same trip 6 times since and the mpg was always between 28.2--32.5.I had the AC on 3 of the times,and the wind was blowing at me 3 of the times.
 

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1990 Cadillac Eldorado 4.5 PFI
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63 Posts
Depends on how fast I am going. If I set the cruise at 65mph, with very little headwind, my 90 4.5 averages 29-30mpg with the A/C on. Cruising at 72mph, A/C on, I average 26.5-27.5 mpg. About as good as it gets for a V8 powered anything!:)
 

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Past: 95 Fleetwood, 91 Brougham. Now: 92 Lexus SC300
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5,418 Posts
You guys are getting fantastic mileage! What sort of MPG do you average with daily driving?

Just for comparison sakes, my 1991 Brougham with the 350 V8 got me a best of 23.5mpg on a road trip. I'm sure it would've done better if I didn't drive 85mph the whole trip, but it was just me in the car. It usually gets 17-18mpg in my daily commute.
 

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1985 Cadillac Seville Elegante
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222 Posts
My 85 Seville city will do around 18 but thats cuz its weight lets me easily coast down any hill or after making it to 30+ an hour till the lights. I just got home from a Grand Marais trip back home here to Minneapolis and it was about 27.1 average. Again its amazing the coasting you can get in this engine with the weight of some of these cars I think.
 

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1998 Seville STS / 2013 Chevrolet Impala
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These 4.9's are gas sippers, and they're designed to run rich from the factory. I bet with a good tuner and some patience, you could get even better mileage then what is reported here.
 

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1985 Cadillac Seville Elegante
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222 Posts
Yea if you arent hauling ass with 3 people and a full cabin load like I was it should get higher. I am running on a 4.1 myself so I am damn happy.
 

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2011 Crown Vic LX, 2009 Chevy Malibu 2LT
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5,607 Posts
Discussion Starter #11
My average commute will get me about 18-19 mpg's in the '95 and 1 or 2 mpg better on the '90.

However, I noticed on all 4 of my 4.x powered cars I've owned that these motors take a significant hit in the winter. I know all do, but the hit on these seem greater than my other vehicles that have included a 2.8 and 3800. During WI winters, I've had my '95 4.9 sink down to 15 mpg's
 

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1985 Cadillac Seville Elegante
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222 Posts
Yes I hear ya. My trip to lutsen in February was a tank and a quarter. It was the blizzard and all but winter kills.
 

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83 Eldorado, 90 Seville, 94 Concours
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469 Posts
My daily driver, a 90 Seville 4.5 with 297,000 showing, averages 18-19 city & 22-24 highway year round. My 83 Eldorado HT4100 with 45,000 showing is averaging 16-17 city, and 21-22 highway. summer use only. Both running A/C.:cool2:
 

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1985 Cadillac Seville Elegante
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222 Posts
They said these engines don't get miles. How have you all maintained to 150k plus? I'm only at 92k currently
 

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Past: 95 Fleetwood, 91 Brougham. Now: 92 Lexus SC300
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5,418 Posts
They said these engines don't get miles. How have you all maintained to 150k plus? I'm only at 92k currently
The 4.1 V8 in your Seville is the problematic motor. The 4.5 and 4.9 V8's are much more durable and really don't have any major issues/design flaws like the old HT4100.

For people who says the mileage goes to crap in the winter, it could be the gasoline. There is a summer and winter blend for many different regions of the country.
 

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1998 Seville STS / 2013 Chevrolet Impala
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They said these engines don't get miles. How have you all maintained to 150k plus? I'm only at 92k currently
If you add up all the 4.9s that have been in my household, the mileage equates to just over 700k :thumbsup:
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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1,673 Posts
I`ve always wondered why Cadillac stopped production of the 4.9 liter in 1995 in favor of the Northstar.Just when they basically fix all the problems with the 4.1 and 4.5 liter engines,they pull the plug on the 4.9.----it`s a damn good reliable engine,when properly maintained.
The 4.9 is less complex and much less problematic than the Northstar.
 

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83 Eldorado, 90 Seville, 94 Concours
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469 Posts
The 4.1 V8 in your Seville is the problematic motor. The 4.5 and 4.9 V8's are much more durable and really don't have any major issues/design flaws like the old HT4100.

What can I say. They both run great. no major problems with the engines, just usual stuff like CV's, struts, brakes, bat, alt, tires, belts, and filters. I did have to have all the injectors serviced on the Seville after my daughter put diesel in the tank accidentally.:banghead:
 

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69 Thunderbird | 90 Seville | 03 Corolla | 89 Marquis(scrapped) | 72 Torino(scrapped)
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2,026 Posts
What can I say. They both run great. no major problems with the engines, just usual stuff like CV's, struts, brakes, bat, alt, tires, belts, and filters. I did have to have all the injectors serviced on the Seville after my daughter put diesel in the tank accidentally.:banghead:
Lmao! Did it run on the diesel at all? I bet it made a ridiculous smoke cloud!:histeric:

At least she didnt put NoS energy drink in the tank! http://www.cadillacforums.com/forum...ge-member-introductions/170073-epic-fail.html
 
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