Gas mileage info - our recent trip

Started by David #19063, March 25, 2005, 11:04:17 AM

Previous topic - Next topic

David #19063

To all,

I thought I would share the gas mileage of my wifes 96 Concours and my 94 Fleetwood Brougham on our drive yesterday up to western Wisconsin.

Gas mileage was calculated by filling both cars (topping the off until theyd take no more) at the same time right before we got on the highway.  Premium in both.

Driving NW into the wind...usually, on the return drive home we do get a little better mileage.

Since it was cold out, running both cars in the "ECON" mode so the AC compressor would not kick on...this can make 1-2 mpg difference.  For best mileage when AC is not needed, I suggest you run in the "ECON" mode all the time.

96 Concours, 209" long, front wheel drive, 245 50WR 16 tires, 3.71 transaxel, 300 hp 4.6L Northstar.

94 Fleetwood Brougham, 225" long, rear wheel drive, 235 70R 15 tires, 2.93 transaxel, 260 hp 5.7L LT1.

We filled both cars again to the top just before our destination.

The Concours said "E" and took 17.436 gallons.  It has a 20 gallon tank that can hold just over 21 gallons.

The Brougham said 1/4 tank and took 18.812 gallons.  It has a 23 gallon tank that can hold just over 23.5 gallons (before she runs out of gas...LOL!  The digital gas gauge in this car drops very quickly the last 1/4 tank and it WILL run out of gas very very very quickly after the "Low" light comes on!)

The Concours showed 436.5 miles.

The Fleetwood showed 428.6 miles.

(This discrepancy, I believe is due to the slightly lower ride height of the Concours 245 50WR 16s that I had put on it.  Should have bought 255s I guess.  Stock is 225 60HR 16s or optional 235 60HR 16s.  But the car looks so much better with the 50s and handles better too.)

So using the mileage for each car.

Concours = 25.0 mpg
Brougham = 22.8 mpg (23.2 mpg using the Concours 436.5 miles)

The computer in the Concours said it got 24.1 mpg...usually, the computer always reads high, which is frustrating...but if you really top off the tank, I think it confuses it.  The Brougham does not have a computer...or a tach, temp guage, oil pressure, etc...just idiot lights.

I thought that this was excellent mpg for both cars as we travelled at 77 mph.  Although sometimes faster when following other cars, and a little slower in parts of Chicago.

So based on this mpg and say the tank capacity of 20.0 gallons and 23.0 gallons, it give a cross country tankful driving range of:

Concours = 500 miles
Brougham = 524 miles

NOTE:  Since the 96-99 DeVille (& DeElegance) use a 3.11 transaxel as opposed to the Concours 3.71 transaxel, I would expect them both to get better gas mileage than the Concours.

Just thought someone might like to read this data.

PS.  I think the 2000+ DeVille/DTS has a smaller gas tank, eg. 18 gallons.

Michael Stamps 19507

Ive got to get a LT1 Fleetwood to replace the Audi.  You are getting about the same mpg that I get and I bet you have better stright line performance.  Not sure how the Fleetwood would handle the curves though.


David #19063

Hey Stampie,

Youd love one!

It rides like an ocean liner...and steers like one two...LOL!  I love it!

Curves?  There are no curves in the ocean!?!

Actually, I read somewhere that that the Fleetwood was given a stiffer suspension than the Roadmaster or Caprice.

If I were you, I would get a 95 or 96 and not a 94.  the traction contol on the 94 is miserable...neuters the car, applied too much brake and makes the car upshift while leaving you near stalled in the intersection.

I pretty much turn it off every time I drive it.


Michael Stamps 19507

What trans do they come with?  If its the 4L60E I can get a manual valve body for it and really have some fun.


David #19063

Yes, I believe all three years had that trans.

What you want to do is find one with one of the two towing packages that have the 3.42 limited slip rear.


Morgan Murphy, No. 17409

I bought a "new" 1957 Eldorado Biarritz yesterday and drove it home from Dallas, Texas to Birmingham, Alabama.  The gas needle, dead as a doornail for the first 100 miles reading a quarter-tank, suddenly came to life near Longview, Texas, reading almost full.  At the next fill-up, after about another 100 miles (when it was reading a quarter tank), it bobbed right up to "F."

The old car got to running so well, the miles started to click by.  And if you live in the South and looked outside on Friday, you know it was a beautiful day!  After Id cruised 240 miles, I guess I either got carried away or the scenery and the new convertible went to my head.  Anyway, I suddenly felt the engine skip.  Uh-oh.  Luckily, I was near an exit, so I pulled off.  The engine croaked at the top of the ramp.  It croaked again under the overpass.  I clicked on the electric in-line fuel pump, she fired up once more and I literally coasted into the gas station on fumes.  She ran out of gas next to the pump!

Thats called finding out she only gets 11 mpg the hard way!

Keep coasting!  LOL!