How many miles per gallon did the 1970's Cadillacs get?

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Wahsapa

Diamond Member
Jul 2, 2001
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a friend of mine got a 72 sedan deVille off craigslist for 1400... which is about as much as he used on gas for the 6 months he had it. before he sold it because he couldnt afford the gas to drive it.

driving around town all day requires a tank of gas. driving on the free way we could watch the gauge go down.

got him laid tho :thumbsup:
 

eldorado99

Lifer
Feb 16, 2004
36,324
3,163
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Originally posted by: Iron Woode
Originally posted by: eldorado99
Anyone have any ideas?
How about some intelligent opinions?

Ok, is this a daily driver? Is this a project car for cruising? Is it both?

Mileage isn't the greatest usually in the 12 mpg city range.

The larger cars came with 27 gallon tanks.

These cars were downsized in 1977, like the other fullsize GMs.

I drive a fullsize 1987 Crown Vic that manages, on a good day, 18 MPG, but usually 15 or so.

But if you enjoy big cars, like me, then mileage is not important.

I do enjoy big cars.. very much, however mileage is still somewhat of a concern because I have a small income. This car would be a project and then cruiser/daily driver once it is fixed up a bit.
 

Summitdrinker

Golden Member
May 10, 2004
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if want a big car thats easy on gas get a 94 or 95 or 99 to 2002 mercury grand marquis or ford crown vic 25 to 26 mpg on the highway is possible average mpg is 18 to 22 depending on driving conditions and habits

96 to 98 were ok too but can have bad intakes that crack

lincoln town cars also, same years

overall very good cars
 

jkersenbr

Golden Member
Jun 22, 2000
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My mom and dad had a 1977 Cadillac Sedan Deville with the 425 V8. It got about 17MPG with normal driving. Man it was fun to drive. Lots of muscle, real quiet interior, rode like a dream.

Good mileage for the power and size. The thing was as heavy as a pickup.
 

eldorado99

Lifer
Feb 16, 2004
36,324
3,163
126
Originally posted by: jkersenbr
My mom and dad had a 1977 Cadillac Sedan Deville with the 425 V8. It got about 17MPG with normal driving. Man it was fun to drive. Lots of muscle, real quiet interior, rode like a dream.

Good mileage for the power and size. The thing was as heavy as a pickup.

Really? it got 17MPG?
 

Summitdrinker

Golden Member
May 10, 2004
1,193
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yep some of the later cads with the 425 weren't to bad on gas if you drove right, I knew people who averaged around 15 to 17 mpg and got higher on trips. they didn't have lead feet thou

other big cars of the day that could be fairly easy on gas were some of the mopars with the 360 engine
 

Iron Woode

Elite Member
Super Moderator
Oct 10, 1999
31,349
12,844
136
Originally posted by: eldorado99
Originally posted by: Iron Woode
Originally posted by: eldorado99
Anyone have any ideas?
How about some intelligent opinions?

Ok, is this a daily driver? Is this a project car for cruising? Is it both?

Mileage isn't the greatest usually in the 12 mpg city range.

The larger cars came with 27 gallon tanks.

These cars were downsized in 1977, like the other fullsize GMs.

I drive a fullsize 1987 Crown Vic that manages, on a good day, 18 MPG, but usually 15 or so.

But if you enjoy big cars, like me, then mileage is not important.

I do enjoy big cars.. very much, however mileage is still somewhat of a concern because I have a small income. This car would be a project and then cruiser/daily driver once it is fixed up a bit.
Hmmm....

My advice would be to not go overboard with the heavy options. Make the car as light as possible. And tune the engine for max effeciency. Also these cars didn't come with serious gearing, so you will probably have "highway gears". Find the best ratio for off the line oomph and mileage.

But all the advice is useless unless we know specifically what car you had in mind including year.

PS: CMD is a great source for caddy performance.

PPS: did you know the factory intake manifold has the carb sitting below the heads intake ports? Guess how inefficient that is.
 

squirrel dog

Diamond Member
Oct 10, 1999
5,564
48
91
Yo Eldo , is this an inside deal , like mom/dad/grandpa/ma's car at a give away price ? I had four cads all got fair to midllin mileage for their time . The best was a 1978 Coup Deville(425 cid)the worst was the fleetwood broghams I got into . One had the horrible 8/6/4 cyl engine. Another had the very bad 4100 alum. engine . Keep in mind they all have a lot of stuff on them(auto air shocks for instance) this can leave you bleeding at the repair shop .
 

eldorado99

Lifer
Feb 16, 2004
36,324
3,163
126
Originally posted by: Iron Woode
Originally posted by: eldorado99
Originally posted by: Iron Woode
Originally posted by: eldorado99
Anyone have any ideas?
How about some intelligent opinions?

Ok, is this a daily driver? Is this a project car for cruising? Is it both?

Mileage isn't the greatest usually in the 12 mpg city range.

The larger cars came with 27 gallon tanks.

These cars were downsized in 1977, like the other fullsize GMs.

I drive a fullsize 1987 Crown Vic that manages, on a good day, 18 MPG, but usually 15 or so.

But if you enjoy big cars, like me, then mileage is not important.

I do enjoy big cars.. very much, however mileage is still somewhat of a concern because I have a small income. This car would be a project and then cruiser/daily driver once it is fixed up a bit.
Hmmm....

My advice would be to not go overboard with the heavy options. Make the car as light as possible. And tune the engine for max effeciency. Also these cars didn't come with serious gearing, so you will probably have "highway gears". Find the best ratio for off the line oomph and mileage.

But all the advice is useless unless we know specifically what car you had in mind including year.

PS: CMD is a great source for caddy performance.

PPS: did you know the factory intake manifold has the carb sitting below the heads intake ports? Guess how inefficient that is.

Well there is a 78 Coupe Deville with a 425cid around here somewhere that can be had for 1500 bucks, if its in good shape I may purchase it. Thats a good idea with the weight reduction, that may get it down to more reasonable levels. This could be a very interesting project. There is also a 71 Sedan Deville around with a 478cid. I don't like sedans as much as I like coupes and the 478 would only make the mileage worse so I suppose I might as well go for something more like the 78. Then again there is a lot I do not know about with the emissions controls from each year and such. Your thoughts?
 

eldorado99

Lifer
Feb 16, 2004
36,324
3,163
126
Originally posted by: squirrel dog
Yo Eldo , is this an inside deal , like mom/dad/grandpa/ma's car at a give away price ? I had four cads all got fair to midllin mileage for their time . The best was a 1978 Coup Deville(425 cid)the worst was the fleetwood broghams I got into . One had the horrible 8/6/4 cyl engine. Another had the very bad 4100 alum. engine . Keep in mind they all have a lot of stuff on them(auto air shocks for instance) this can leave you bleeding at the repair shop .

Unfortunately no it isnt an inside deal, the main Caddy I'm looking at right now is a 78 Coupe Deville with a 425 just like you had. I wish my grandpa would have kept his 79 Fleetwood for me but he traded it in before I was born :p.
 

Summitdrinker

Golden Member
May 10, 2004
1,193
0
0
if your worried about gas mileage don't buy a old caddy, get something easier on gas, you will most likely will have to make repaires too, this will cost ya some cash
 

0roo0roo

No Lifer
Sep 21, 2002
64,795
84
91
make repairs? its basic requirement of cars that old. things wear out. something that old is a hobby car for people who know what they are doing and have the money for parts. and it shouldn't be a daily car if you care about the air. emissions back then were rather bad.
 

grrl

Diamond Member
Jun 21, 2001
6,204
1
0
My parents had a 70s vintage Sedan deVille and it got about 12 mpg. Not bad considering their Lincoln got about 8.
 

eldorado99

Lifer
Feb 16, 2004
36,324
3,163
126
Originally posted by: Summitdrinker
if your worried about gas mileage don't buy a old caddy, get something easier on gas, you will most likely will have to make repaires too, this will cost ya some cash

I am aware of having to make my own repairs, for me thats part of the fun. I am by no means a gearhead... yet, in other words I am very enthusiastic about learning to work on cars. I know some as of now but I would like to learn more. Although how much would you guess it would end up costing for a car that old to repair?
 

Summitdrinker

Golden Member
May 10, 2004
1,193
0
0
old cars like that may need odd stuff, for example if it a car that was driven in salt the brake lines maybe rusted, cheap to fix but lots a work, old cars often need new radiators, cost 200 dollars maybe more. parts for caddies aren't cheap and maybe hard to find

how about worn out ball joints, cost of brake parts??????

and the big thing with caddies can electricial problems, like power windows etc

junk yard parts maybe hard find??????????
 

eldorado99

Lifer
Feb 16, 2004
36,324
3,163
126
Do you have an estimate as to how much it would likely end up costing me to repair a car that old to be driveable? (There is a smog test where I live)
 

Summitdrinker

Golden Member
May 10, 2004
1,193
0
0
it just depends on the condition, luck, and how it was taken car of before

pretty hard to put a dollar value for repairs on a car that I have never seen