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Thread: Incredible good mileage 1984 Town Car CFI

  1. #1

    Default Incredible good mileage 1984 Town Car CFI

    Hey guys, just wanted to let you know that I experienced incredible good mileage with my 1984 CFI Town Car on our family trip this weekend.
    19.7 mpg at an average highway speed of 70mph. But that was fully loaded with 6 passengers (4 adults and two teens) plus our dachshund, the trunk filled with luggage to the top, AC on all the time to defog and headlights on also. Oh, and winter/snow tires.

    That was on E5 gasoline which contains 5% ethanol. Running E10 dropped fuel economy to 17.3 mpg.

    How can this be? Am I dreaming? Nobody believes me this american landyacht is so good on fuel.

  2. #2
    Carthago delenda est Lutrova's Avatar
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    Having that fourth, overdriven gear really makes a difference. Makes me wonder how a Barge would perform if you threw an AOD in it.

  3. #3
    Lost and driftin' Arquemann's Avatar
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    I'm really hopeful on getting improved mileage when I get my carb swap done, since the CFI effed up any remnants of good MPG. The idea of getting a panther for me was to get a classic-looking boat with okay gas mileage.
    Box panthers might look like massive barges, but they weigh under 2 tons unladen and do have that overdrive.

    Quote Originally Posted by Lutrova View Post
    Makes me wonder how a Barge would perform if you threw an AOD in it.
    A guy I know has a barge Grand Marq coupe, '77 with the 400 2bbl and FMX, supposedly gets 20mpg at cruising speeds, 55-65 mph.
    1985 Mercury Grand Marquis LS, "Maisa"
    2008 BMW 530d Touring, "Femma"

  4. #4
    GMN Regular DerekTheGreat's Avatar
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    Being the site's leading skeptic and pessimist, I question the accuracy of your speedometer & odometer and how you were filling the tank at each stop.

    I squeaked 24.xx out of my '88 Town Car once. Odometer accuracy verified by mile-marker and I always filled the tank such that a little gas was always standing in the fuel filler neck, like just past the copper flappy flap.
    1985 LTD Crown Victoria - SOLD
    1988 Town Car Signature - Current Party Barge

  5. #5
    all the CFI are belong to me
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    I've clocked 21 US MPG with my 84 in similar conditions (I think my speed was higher though, which is what makes my story less believable). Filled tank, hopped on the highway, drove at steady speed to destination just off highway. Got back on highway, drove back to same gas station, filled tank again. Did math based on fuel I had to re-add, and actual distance travelled.

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  6. #6
    2 decades of DDing Box Panthers, now in a Whale VicCrownVic's Avatar
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    For me the numbers are very believable and I was going to say Hillbillycat's numbers are actually a little low (not far off though). Kishy's number confirms that initial thought, although from my experience his number is at the high end of the spectrum at that speed (different cars with different options and gear ratios affect the number.) For me the numbers are believable because I've been around these cars for so long and have been on some long road trips with mine.
    Vic

    ~ 1998 Mercury Grand Marquis LS - new DD
    ~ 1991 Mercury Grand Marquis LS "The Scab" - plenty of rot, backup/summer cruiser
    ~ 1997 GMC Yukon SLT - wannabe winter DD - many issues, returning sometime in the 2020s
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  7. #7
    GMN Regular WagonMan's Avatar
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    My newest 89 Colony Park sips gas, (2.73 gears) My other 89 CP has 3.55s, (K code car), it drinks gas!!!! WagonMan
    1990 Colony Park
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  8. #8
    Beater gonna beat sly's Avatar
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    The 88 MGM I had pulled off 22 normally with E10 fuel. 24 when it was E0. That was when it had 2.73 open rear. After the WR-AOD and 3.55L rear modifications, never got better than 21. And that was doing 65mph tops. still get 19mpg at 80 though. I think that had more to do with the rounded corners and not catching quite as much air as the 79-87 cars. The 93 pulled off 28 mpg several times with 2.73 rear gears and E0 fuel. E10 was 26 max. With the PI swap and 3.55L rear mods that dropped to 21. Since the j-mod, I've not taken a trip in it but my city went from 15 to 16.5-16.7 on the regular, so I might manage 22-23 highway instead of just 21.

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  9. #9
    Road Warrior Kodachrome Wolf's Avatar
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    Best the '87 ever managed was 21 MPG prior to dual exhaust and HO conversion with a 3.27 open rear gear. I don't think it's done any better than 18 since being converted, but I haven't done any "economy" runs. Usually I'm running 75+ MPH down the highway, but it's old sweet spot was 65-67.

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  10. #10
    I'm an air-conditioned gypsy gadget73's Avatar
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    When CFI is right, its actually pretty decent on fuel. The problem is they are often not-right.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  11. #11

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    I calculated 21 MPG in my 1988 Town Car after a total 140 mile highway round trip, with radial pull from bad tires the whole way, no AC and carrying 4 HPP rims on the return half. Odometer is accurate. I've been too lead-footed to try for any better since.

  12. #12
    fomoco panthers !
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    My 1996 CVPI averages 22 in town, up to 28 on a trip.
    The 1990 CV averages 18 town, 22 on a trip
    The 1989 LTC averages 18 town 21-22 on a trip
    The 1989 LTC g signature gets 11-15 in town depending on traffic. 22 on a trip

    Factors that impact my gas mileage is using Ethanol Free gas at Citgo. Best mileage is obtained with Shell Premium (summer blend)
    Sam's club gas is ok but mileage is down. That gas is not good to use long term.
    Speed. If I can keep the speed at the sweet spot of 62mph, I get great mileage. 70 brings it down. Over 70, don't want to know.
    Tire inflation is at 32 lbs cold. Ambient air temperature makes a difference.
    Not using the cruise control.

  13. #13
    What a Luxury car should be. mercurygm88's Avatar
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    That sounds about right to me. Over the 4,000 miles I put on the Mark VI between June 28 and last Wednesday when I garaged it for the winter I averaged about 19 mpg, I never took it on any long road trips. I'm lazy and my right foot cramps really easy, I use cruise control all the time. This being a 36,xxx original mile CFI car that according to the records I have sat unregistered from 1999 until early 2021. it's sure been mighty reliable for a car that sat for so long.

  14. #14
    I'm an air-conditioned gypsy gadget73's Avatar
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    My own notoriously unreliable car sat for a decade and has just shy of 200k. All of the stuff works despite everyone saying the diesel engines were a complete pile. It also does a solid 25 mpg around town and about 29 on the highway. Of course with the higher price of diesel thats cost-equivalent to about 22 mpg last I did the math.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  15. #15

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    I validated my speedometer with the gps from the navigation system. Its accurate. And of course I had made sure to fill up to the neck. So I think my readings are correct, though Id love to get better mpg, of course.

  16. #16
    Lost and driftin' Arquemann's Avatar
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    Quote Originally Posted by Hillbillycat View Post
    though Id love to get better mpg, of course.
    SEFI swap, make it breathe better, throw the Thermactor crap into a pond and get like 2.47 gears
    Then again you're driving a BOAT that was designed with a straight edge and cocaine.
    1985 Mercury Grand Marquis LS, "Maisa"
    2008 BMW 530d Touring, "Femma"

  17. #17
    I'm an air-conditioned gypsy gadget73's Avatar
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    honestly I don't really think you'd get much improvement out of multiport on the highway. Around town probably, those long runners make more torque down low.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  18. #18
    2 decades of DDing Box Panthers, now in a Whale VicCrownVic's Avatar
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    Quote Originally Posted by Arquemann View Post
    SEFI swap, make it breathe better, throw the Thermactor crap into a pond and get like 2.47 gears
    Then again you're driving a BOAT that was designed with a straight edge and cocaine.
    2.26 was an option on '79 panthers (maybe other early years), that's what Grand1 has in his '79 Marquis. Hillbillycat has the same problem as you, he's on the wrong side of the world to just find panther parts like I can in Detroit. Makes swapping to factory options from other years a little harder/more expensive.
    Vic

    ~ 1998 Mercury Grand Marquis LS - new DD
    ~ 1991 Mercury Grand Marquis LS "The Scab" - plenty of rot, backup/summer cruiser
    ~ 1997 GMC Yukon SLT - wannabe winter DD - many issues, returning sometime in the 2020s
    ~ 1991 Mercury Grand Marquis GS "The Ice Car" - Rotting Retired Winter DD
    ~ 1989 Mercury Grand Marquis GS - Rotting Retired DD
    Gone but not forgotten:
    ~ 1988 Country Squire ~ 1987 Ford Crown Vic

  19. #19

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    Exactly
    BTW Thermactor stuff is longe gone.

  20. #20
    GMN Regular DerekTheGreat's Avatar
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    Quote Originally Posted by VicCrownVic View Post
    2.26 was an option on '79 panthers (maybe other early years), that's what Grand1 has in his '79 Marquis. Hillbillycat has the same problem as you, he's on the wrong side of the world to just find panther parts like I can in Detroit. Makes swapping to factory options from other years a little harder/more expensive.
    The 2.26 was probably only available with the tree speed trans. Would need to swap that tall thing in if a fella wanted it, for some unbeknownst reason. Another thing to keep in mind is that just because you made the engine turn slower at a given speed, doesn't mean it'll also use less fuel. Ever try riding a bike up hill in a high gear? Legs going slow, but holy hell what a sweat.
    1985 LTD Crown Victoria - SOLD
    1988 Town Car Signature - Current Party Barge

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