Real World Gas Mileage Numbers Please

[Road_Runner]

I've got a 70 Roadrunner that I (almost) could care less what gas mileage it gets as long as its faster then hell.  My goals for my 73 Barracuda I recently picked up are very different.  It has the makings of a really nice semi-daily driver: PS, PB, Air, Slap Stick Auto, etc. and the driveline is a 318 2 bbl, 904 auto & 8.75 rear.  What I'd like to know is for those of you that drive your cars enough to actually know the miles per gallon you get I would greatly appreciate know what it is and the driveline combo you're using.  I've had very powerful cars (95 T/A, 2003 Vette) that also got great gas mileage.  I'd like to make the Cuda as close to these as I can.  Fast enough without pushing the MPG down towards single digits.

Thanks in advance, Jim

[moparmaniac59]

I had a 73 Barracuda with everything you described, (318, auto, air ect). It had an interstate gear (approx 2:73) and on the interstate w/o running the A/C I think I got upwards of 18 MPG. I now have a '74 Challenger that's not much on MPG's as it has a 543 BB stroker with 1000 CFM carb and 3:91 posi. I think on a good day it might get 8 MPG!!! But then again, I didn't build it for mileage, I built it for SPEED. So I can beat you to the gas station LOL!!!


                                                   Matt B.

[Chryco Psycho]

I have tuned 318s to get 22+ MPG with mild combos , I have been able to get close to 20 MPG from 440s as well using the US gallon

[Oldschool]

The Beast gets about 10 mpg when I drive it around easy on the street.  Not bad for what it is.....   

[Supercuda]

When my 383 was 425hp, I got 16mpg on the highway in my '71 Satellite. She had a 727, and 2.71:1 rear gears. 235/60R15 tires. In my '67 'Cuda, at 470hp on E85, she gets 7mpg with 295/50R15, and 4.10:1 gears. Before I switched to E85, I was getting 5mpg on gasoline.

[72hemi]

I have a 72 Challenger with a 70 340 (with a 750 cfm carburetor), 727 and 3.23 gears with power disk brakes and manual steering and I get around 8 mpg around town, but a large part of that is I have a 3.5 mile commute to work and I spend more time letting the car warm up than I do actually driving to and from work. On the Highway I get close to 15 mpg. I am planning on one day installing an overdrive and fuel injection and hoping to get my highway mpg above 20 mpg and my around town to the mid teen's, but time and money will tell on that one.

[BB73Challenger]

I have been able to get close to 20 MPG from 440s as well using the US gallon

What!?! rolling down hill with the wind behind you, right 

[HP2]

74 Plymouth has a bone stock (low compression) 360 with small Summit grind cam and  a 650 4bbl and gets 15 highway. Not exactly a power house though.

The built 440 in my 73 truck will get 18 on the highway, which aint bad for a 3 spd auto and 4:11 gears. It is a basically stock rebuild, only with really high compression and a 750 4bbl with, again, the small summit cam. This thing has torque like a diesel, but runs out of steam around 5000 rpm. A bigger cam would change that but may compromise the fuel usage though.

IMO, dynamic compression optimization is the key to not only power, but also efficiency. Building an engine with a very low torque peak and then matching the cruising rpm to be within the high point of that range will give the best mileage.

[0tter45]

I have a 74 cuda with a small block stroker around 525hp.  It has a 950cfm carb.    At 62mph  my rpm is around 2600rpm.  I used my wide band to lean out the afr  to 15.2-1  and run about 48 deg advance in cruise.  With this set iam getting 23 mpg.  I bet if you look at 90 percent of the exhaust pipe on muscle cars they will be black as coal.  My cars are a nice light brown.  Old school carbs from the 60 were set up to give good milage and performance.  All the new carbs are set up to  be pig rich all the way thru and give poor milage.  You need to do alot of tweaking to bring things back to were they should be.


Otter

[Aussie Challenger]

My '70 Challenger got 17 mpg US on the 1,800 mile trip across America. It was loaded up with spares including a spare engine where the passenger seat should have been.
318 4 bbl, mild unknown cam, headers, PS, 904 and 3.23:1 diff, cruising between 60 - 85 MPH on open road. Auto is a little tired but kept me moving forward.   

[whitesatinmopar]

Our Chally has a mild built 360 with 7 1/4 rear (2.73) it usually gives us 14-18 mpg highway. Neil had his fingers on it a few years ago and other than sparkplugs nothing has been touched since in the tuning department. Our other cars we just expect enough MPG to either get to a gas station or home, whichever is closer. 

[70burntorangeT/A]

taking it easy on the highway my 440 in my chally gets 16mpg or so, but i have 3.23 gears and only a 600cfm carb. Im upgrading to an 850 this summer and i figure the milage will get cut in half. Rodding it around town (which is the majority of my miles) it gets about 5mpg

[JayBee]

318/904, 600cfm, 340 exhaust manifolds, 3:23 SureGrip, cam(450 lift/290 dur.)

Best highway only= 17.5mpg
Avg city/highway = 13.5mpg...both figures using US gallons

The mileage would probably improve if I slowed down on the highway and didn't use the slapstick so much.

[Carlwalski]

The Beast gets about 10 mpg when I drive it around easy on the street.  Not bad for what it is.....   

Holy crap, that is good for the Beast. I think SRT/10 Rams are factory quoted for 12-13mpg, stock.


My Challenger gets around 17-18mpg+ depending on roads, this is if I drive normally without WOT runs and conserving gas. With the future camshaft, intake and carb upgrade this figure will drop LOL. It has a TF727, 3.91 gears with OD = 3.23 and the engine is basically stock (438 lift/214 dur) with a 800cfm AVS Edelbrock and tti headers with x pipe exhaust system.

[JayBee]

My Challenger gets around 17-18mpg+ depending on roads, this is if I drive normally without WOT runs and conserving gas.

Carl, just curious, is that converted to US gallons? Are NZ pumps in litres? Your numbers are really good too, guess I need to do some slowing down or work on the 318.