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2001 STS
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Discussion Starter #1
I'm coming from Texas and there and back, I've been getting 20 mpg. I've been doing 77-80 mph. Is this decent?
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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Re: 2001 Seville STS mpg

I'm coming from Texas and there and back, I've been getting 20 mpg. I've been doing 77-80 mph. Is this decent?
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it's exactly what I would expect from an STS going 80 -
 

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2006 STS V8 1SF RWD
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6,479 Posts
Slow her down a bit and she'll be even more efficient! :thumbsup:

20mpg from a 2+ ton pig with a V8 isn't so bad....

I've seen 23-25 with mine on extended trips, definitely not at 80 though. All down hill after 65-70mph.
 

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2001 STS
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315 Posts
Discussion Starter #4
curtc said:
Slow her down a bit and she'll be even more efficient! :thumbsup: 20mpg from a 2+ ton pig with a V8 isn't so bad.... I've seen 23-25 with mine on extended trips, definitely not at 80 though. All down hill after 65-70mph.
Yea I think she's doing pretty well. My very first sts was a 97 and I would get 27 highway with her. She had a complete tune up and around 112k. Triple black with a good buff. She looked good.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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I get 25 mpg on 87 during our Florida trips - 820 miles one way on I-95 and 301 - so speeds vary from 55 to 80.

Here's where your rpm should be at various speeds, above 43 mph with TCC engaged. (Courtesy of mhamilton with input from a dozen FWD Northstar drivers.)
 

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White Diamond '03 DHS (with DTS floor shift)
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I would venture a guess that 80 MPH is not the most fuel efficient speed and that 20MPG at 80 is probably about right for an STS.

It would be really interesting to see a speed vs fuel efficiency graph to see what the optimal speed would be for the best fuel efficiency.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Based on limited fooling around with this, about 50 mph, flat road, steady speed is the absolute ideal for economy. Some days, 45 looks good. Some days, 53 looks good. Anything over the mid-50s and economy falls off, and over 75 or so it falls off rapidly.
 

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2001 STS
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Discussion Starter #9
I noticed I got MUCH BETTER mpg if I used mid grade, which is 89 I believe. Seemed like the 87 burned a lot quicker. Also my TCC is no good, so 20 mpg I don't think is bad at average 77. Was wondering what you all were getting on your trips.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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There is no fuel mileage difference between octane ratings. The car has no idea what octant is in the tank, there is no more energy in higher octane fuel, the same amount of fuel is injected into the cylinders, nothing changes.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
Joined
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19,273 Posts
I noticed I got MUCH BETTER mpg if I used mid grade, which is 89 I believe. Seemed like the 87 burned a lot quicker. Also my TCC is no good, so 20 mpg I don't think is bad at average 77. Was wondering what you all were getting on your trips.
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I noticed I got MUCH BETTER mpg if I used mid grade
ALL RIGHT - :highfive: - :cheer::dance7::luvu::florian:

GAS WAR - :mob::cursin::banghead::emocide::aj:
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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Based on limited fooling around with this, about 50 mph, flat road, steady speed is the absolute ideal for economy. Some days, 45 looks good. Some days, 53 looks good. Anything over the mid-50s and economy falls off, and over 75 or so it falls off rapidly.
Thanks Jim :thumbsup:

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There is no fuel mileage difference between octane ratings.
:yeah: :nuffsaid:
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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I noticed I got MUCH BETTER mpg if I used mid grade, which is 89 I believe. Seemed like the 87 burned a lot quicker. Also my TCC is no good, so 20 mpg I don't think is bad at average 77. Was wondering what you all were getting on your trips.
If the TCC is dead, that's the mileage difference. It accounts for a ~300 rpm higher 4th gear.

On 3 of our MD - FL 830 mile one-way runs I used Shell 87 down, Shell 93 back. Absolutely NO mileage differences.

As in the owner's manual, if I'm headed for the track or the old runway the car gets a slug of Shell or Sunoco 93. Otherwise, it lives on 87 with absolutely no problems and the same general fuel mileage........ because the car lives on 87, even if I dump in ??? 6 - 8 gallons of 93 that still says the true octane in the tank is ~90 or so. Nary a problem.
 
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