I ask because I am trying to decide if I should rebuild my 350 or a 455 for my 72 cutlass. I only will be driving the car about 10miles aday or so, mostly in the city.

So any info from you guys would be great.

thanks

 

10 mpg city

 

I averaged 12.6 mpg. on my last tank of fuel. This is in my 71 with a tired old 455 with a 2:56 rear and a decent tune. My driving is mostly city, some rural but NO freeway speeds.

In my opinon, cars guys allways want more power. So I say 455 all the way. The difference in fuel economy is small but debatable.

 

Agreed. both my 455, 350, and 307 all suck equally in this category

 

I have a 70 delta 88 w/455/2bl. I have recentley spent some bucks on it, tune up including carb kit, distributor, plugs/wires everything. Understand I use at least 91 octane, I can get with air conditioning hiway, around 15mpg. City driving is around 10.

 

My 66 Jetstar 88 w/ 330 2 barrel gets around 15 freeway and around 12 or so mixed driving. So the big blocks do as well.

Don

 

what???

 

455, 200 4R overdrive and 3.42 gear. Decent tune with 2.5 inch pipes. I run a 26 inch tall tire and I use lock-up when the car achieves 4th gear. I get 15.5 mix driving. I haven't been on the road enough to know highway MPG.

 

OK, how many of you guys can remember the gas shortage of the 1970's? I drive like an old man most of the time as I learned how to drive with my Dad telling me there's an egg between my foot and the gas pedal... don't break it! The blue car with a fresh 455 4bbl, TH400 and 2.56 gears got high teens on the highway all the time. One trip with four adults in the car and the trunk full of luggage three tanks averaged 21 mpg on regular gas in the 1980's. Later I took that engine out to put in a 1970 442 and installed a 350 4bbl that had been recently rebuilt. Same trannie and rear end got 17-18 mpg on the highway. My job at that time had me traveling throughout Oregon and Washington State so in one summer I put 30,000 miles on the car and that's the consistant milage I got. No idea on city driving, but on the highway with normal driving the 350 and 455 got about the same milage.

 

Gas mileage sucks especially useing the high octane fuel.What really matters is are you haveing FUN driveing you Cutlass?

 

Just have fun driving, Petrol here in England runs around $11.00 a gallon. for the cheap stuff.. 97 over 1£ leter. Andy/

 

I get many sMILES per gallon in my 63 98 convertible!

 

I don't care about mpg because my Oldsmobile isn't going to be a daily driver, but my experience tells me probably would be below 15mpg.

 

Hi :-)

i just got a 77 oldsmobile cutlass 2dr with a 350 in it. It gets 12.5 mixed. this seems a little low.

I made sure the vacuum advance was working, and the carb was recently rebuilt. At idle i think i hear a little miss, maybe a fouled plug or leaky valve?

my other car gets 45mpg and is faster, but i like driving the cutlass.

 

Ugh.... don't remind me.

 

Delta appox 8 to 12 city/highway

Alero 19 to 21 city and highway, 18 to 20 city only, 32 to 35 highway only.

Yes that's right, I can get upto 35 MPG highway with my Alero. That is why I laugh my *** off at commericals for 4 bangers getting 30 to 35

 

Lady got 19.9mpg average during her 1500 mile trip from Georgia to TX, even going though the Blue Ridge and Smokey Mountains and doing 80 though the flats of TX.
She has a 350 4bbl, TH350, and 2.73 gears (I think.)
Puttering around the city has been considerably worse.
If I rent a std suv or a minivan when on vacations and drive the same distance, I get the same avg mileage of 20 with their little V6s.

My Harley gets 58mpg combined city and highway, so there is fun on both ends of the scale!

I think my '86 Cutlass with its 307 and TH200R4 gets around 20 in the city, but not for sure. She does not come out much.

It is all in the fun / style factor. If you can afford it, try not to think much of it (thats what I tell myself...)

 

I have a 69' Cutlass with a 350 4barrel/ I'm not exactly sure on the mileage, but I think it gets around 14 on the highway, and about 10 or 11 in town, maybe less.

 

have any of you ever clocked the total miles to a tank? i remember getting 175 miles to a tank in my 350 2bbl 71 cutlass but now its only getting about 140 total with city and highway driving. most of my mileage is highway so i dont understand how she isnt doing better with gas. stock gear one tire frier and no mods.

 

I'd like to know, but I've never been able to afford to fill that tank!

 

It might get you kicked off the board for swapping the engine, but my DD LS1, T10, 2.73 rear gets low 20s mixed city/hiway. And I cant get the smile off my face every time I drive it

 

I find the milage I realize directly proportional to how far my foot is up that 4 bbl, how fast the little lines are going by, and how straight back my hair is blowing........that being said, I got 19 mpg during a very nice drive out to the Outer Banks, NC last summer with the wife.........with a 350/350 4bbl 69 Cutlass

 

Which trans?

 

Same here.

What does the "smart" car get? Only 32mpg?

 

71 350 daily driver with edelbrock cam, lifters, performer and 600 cfm - 2.72 rear - I get consistently 13 mpg and I don't baby it.

 

Interesting. After 4 years there's an interest in fuel mileage? These old cars were designed when gas prices were around .36/gallon. Or, another way to look at it? $7.20 to fill the tank from DEAD EMPTY.

If mileage is an issue, better to:
1: change to a more economical car
2: change to really low gears (2:56) and install a 200R4
3. take public transit

The only fuel mileage I measure with my 72 is on road trips. When I'm on a long stretch where the gas stns are farther between? I don't let it go below 1/4 tank. Only time I get concerned is if it runs outta gas while I'm closing the door

 

1970 Supreme with 2.73 gears 350CID 15 city 18 hwy
2004 Alero GLS 3.4 V6 4sp auto 3.05 gear city 26 hwy 34 to 35

As a sidebar my 2010 malibu 2.4 4cyl 6speed auto only 34 to 36 hwy

Pat

 

Very true. But remember that 35¢ in 1968 was the same as $2.23 today, the equivalent price of premium (which all of those 4bbl cars needed) was probably more like $2.50, and that $7.20 fill of Regular was equivalent to about $45 today.

Granted that US gasoline prices are at an inflation-adjusted historic high, in line with prices in 1981 and during the Great Depression, but with a $7,000 average annual income, that 35¢ looked a whole lot bigger in 1968 than it does today.



- Eric

 

Average 9-10 mpg.

 

Yup, I remember working in a food store in 74. I earned a whopping 2.36/hr At that time is was above min wage here and we did bust our humps to git'r done. Customer service was critical, and the store paid more for us NOT to have a union.

Every week I'd go to the pay office, get paid in cash and sign for the money. No direct deposit stuff back then I'll tell you. You lose your pay envelope? You're screwed. For some God foresaken reason they liked to pay with new uncirculated money, and lots of 2 dollar bills. On avg I'd make about 45/week. I'd spend about 5.00 of that on gas (sometimes more if I was going to the lake for the weekend - gotta fuel da boat too!) But you're right. I lived with Dad and didn't have to pay rent cause I was still going to school. That was his rule. I offered to pay for stuff, but he would rarely accept. Maybe that's why I feel that way toward my son.

Anyway Eric? Point taken. In perspective gas was not being given away. Just from today's prices, it feels like I'm being legally raped every time I fill the car up.

 

12 mpg in my '71 Supreme, 350 4bbl 3:42's. 13.6 mpg in '70 SX 455 2:56 back when I drove at 60 mph in a 55 zone (1976-1977) 1973 350 4bbl Supreme, 12 mpg, 1977 Supreme 350 4bbl, 18mpg. '71 Supreme ragtop 350 4bbl 2:56 18 mpg.

 

No doubt we all are. The high gas prices are a major drag that led to the economic slump, and are blocking a recovery, at least here in the North (you can live without A/C, but you'll die without heat).

And, yeah, you were doing okay at $2.36. In 1978, I was making $2.35 an hour, which was great because it was a dime above minimum !

Also, it's not your imagination, you can't do as well on the US minimum wage these days as you used to be able to:



- Eric

 

I think you like graphs!

Min wage sadly is NOT indexed to inflation or cost of living. If it was, the min wage parity would be more like back in 74.

YIKES! looking at that chart US min wage in 2009 was only around 7.25??? Here our min wage is 9.40 Back in 2009 it was 8.40 Living in Canada seems to be more expensive for goods and services too.

Even though the $C is close to the $US for the last 2 1/2 years? Our consumer goods prices are about 15 - 20 % higher than yours for exactly the same items. In some cases I think it's retarded that our goods produced IN CANADA are sold in the USA for less than in Canada.

Well, lets not get started on that. This is way beyond the jack limit of a thread.

 

Never really offically checked milage on my custom built 455, but isn't to bad. You really need to take in the whole driveline though. My car has a 700R4 od lockup tranny, and 3.73 axle. The 3.05 1st gear gets the car moving with little effort. The tranny's 0.70 od, is like running a 2.60 axle on the highway. Plus the lockup converter, knocks off a few hundred rpm's too. An intersting thing about carburators. Recall reading, Q-Jets get better fuel milage around town, than two barrels, due to the small primaries. If you noticed, why GM quit using 2 barrels on V8's, after awhile.

 

With stock 350 4 barrel in good tune, 2.73 rear gears, and TH350 in a 74 Cutlass, I got 16-19.

New 362, 3.42 gears, built TH350....well, can you really check mileage a quarter mile at a time?

Theoretically, either engine should get similar mileage if driven modestly, because it takes the same power to move the car regardless of which engine it has in it. Power=fuel and air reaction. The differences that come into play are engine volumetric efficiency, tune, and how often the back barrels come open. If you drive sensibly and have the engine tuned well, you can really take your pick. It all boils down to what kind of power figures you want on tap.
And to quiet the arguments I already hear, I'm talking about a stock to relatively mild build. A car with 12.5:1 compression and a .590 lift cam thats been built to the hilt is not going to get good economy, but at that point, the price of new tires every month would more than likely outweigh fuel concerns.

 

85 Olds Delta 88 307

2.73 gears and 200R4

15-16mpg city & 20-22 hwy

 

I'm getting around 24 highway and 18 in town in my 307 delta 88 with 2:78 rear gear and th2004r trans ...... it's an '85.

 

My stock 231 powered '87 Delta 88 regularly returns 30 mpg (imperial gallons) in normal use and more impressively 22 mpg towing my 1600 lb caravan (trailerhome?).

I remember a old timer friend telling me he traded his v8 '57 Chevy for a Studebaker in 1960 because it gave much better gas mileage. I asked him why when gas was about 18c per gallon, he answered "I had a 400 mile round trip every weekend and a USAF master sergeants pay didn't buy much gas back then after looking after my wife and family."

Roger.

 

Just got back from a road trip( about 600 miles) in the 55 324 engine and averaged out to 12 MPG.I usually get a little better than that but there was a three hour boulevard cruse in there that probably brought it down a couple of MPG...The Idea is to get the most fun out of your MPG not the most dollars out of your gallon....Tedd

 

Went to Niftee Fifties car show last night in the silver car. 60 miles round trip. 1/2 a tank of gas. So I figure 6 mpg, I run 93 octane and 10% C-12 (108 leaded) mix. So every 1/2 a tank of gas costs me $43.00 or so.

And you thought you had it bad...

468ci, Holley HP 950, TH400, 3.42 gear, 26" tire