1986 Cutlass Supreme MPG and milage improvement

[Ericja]

Hey all. First post here so I hope I'm not stepping on any toes or breaking any rules already. Now I'm also sure this is a horse that's been beat to death time and time again but I can't seem to find much concise info on the matter. What's everyone getting? What's anyone done to make it better?

I'm only asking causing gas prices in Canada aren't a joke. But I do need a larger vehicle than I have now. And, for all intents and purposes this vehicle could likely become my daily driver. What say y'all?

Thanks in advance.

 

[L67ss]

Which motor do you have? And trans?

 

[Ericja]

Well i don't have it yet, I'm assuming a vehicle that will be largely stock. So a 305 (common in Canadian versions) with likely a TH200. Now that I'm thinking about it, I'm not sure on the common transmissions in those cars so the above is a guess.

 

[L67ss]

15-25 mpg depending on condition

 

[ed1948]

My Monte Carlo SS, stock 305 get close to 11L/100km(this is the way we do it in Canada) hwy drive like an old man and 15L/100km city. US numbers is around 25 mpg hwy and 18 mpg city. About the same numbers that a new pickup truck gets if driven nicely.
Question - why would you daily an old automobile when there are some many things ready to fail unless it's been maintained to the max?

 

[LukeZ]

I have an 86 305 and a TH200. 2.56 rear end gears and the car weighs about 3700 with me and my tools. Gets crap mileage at about 16mpg on average. I tend to have a lead foot so maybe it could go up to like 20ish. Hope this helps

 

[axisg]

wow Ed, that's impressive. I manage appx 13 mpg city and 20 or so highway in the Monte. Funny mileage didn't seem to change when I went from the 305 to the 350.
FWIW I dd an AWD 2003 Safari work van for 11 years now, I average 13.5 mpg city and 18 on the highway.

I also echo your statement that there are so many cars that would fit the bill better than a 30 year old gbody for DD status

 

[pontiacgp]

Question - why would you daily an old automobile when there are some many things ready to fail unless it's been maintained to the max?

because these cars are basically straight forward which make them relatively easy to find the problem and repair, plus the parts are cheaper than what you find on new vehicles

 

[TURNA]

In 86 the window sticker MGP on an 86 Cutlass were as follows

3.8 3 speed trans 18-22
5.0 3 speed trans 17-21
5.0 4 speed trans 19-23

Going to be hard to beat those numbers

Not to mention those MPG numbers were in perfect track conditions and most likely padded a bit.

 

[pontiacgp]

you'll get better fuel mileage using ethanol free gas