Please list...

Year and car model
transmission
rear gear ratio
tire size
average highway speed
any modifications from stock


Thank you.

Former car
1970 Challenger 340 auto, 3,23 rear.
255-60-15 rear tires

entire power train was 100% box stock. best I think I ever got was around 14-15 mpg

1968 Barracuda, std 4 speed, 3.23, 225X70X14 tires. 71, 340, stock pistons, .480 lift camshaft, headers, lightly ported heads, 71 intake, 72 thermoquad. 22MPG US at 70MPH average. That was running B.C. to Alberta and down to Montana and back.

1971 Challenger T/A
340 6 pack (410 cid stroker) too many mods to list
4 spd
3:91
245/255/60/15 tires
avg speed hwy speed...uhhh...55-60 tops trying to keep the RPMs under 4k
gas mileage...sad, 10MPG with a strong tail wind

Year and car model 73Duster
transmission 904 with a tight custom 3200rpm converter
rear gear ratio 3.21
tire size cant remember but something about the 27" tall
average highway speed 55 Mph or so
Big solid roller cam 260+@0.050
Ported J heads
11:1compression
Holley stripdominator intake manifold.
Holley 650DP carb (i think,i might have had a 800CFM edelbrock tunder AVS but not sure this was 15 years ago.
TTI step headers.
Dual 3"exhaust.
MSD6Abox

with a extremely stable right fot i got the thing down to 28MPG at 55mph Normal highway crusing with a light right fot but alitle faster the thing usualy wanted about 23MPG
Sure miss that thing,but those numbers sure could detoriate rapidly by being just alitle less carefull,this was driving very soft.

Can't believe some of these numbers? 22mpg can't see that
70 Challenger
518 OD
3.73 gears
275/40/18 rear tires
Fitech fuel injection

Car averages 16-17mpg at 70mph
It was 13-14 before the 518 but at 60mph

My 2006 GT Mustang with 3.73 gear and 5spd auto is ~ 19-20 so it seems like it makes sense.

360 Ok?

Year and car model- 1969 Dodge Dart GT
transmission- 727 3000 stall TF2 shift kit
rear gear ratio- 3.23
tire size- 27"
average highway speed- 60MPH
any modifications from stock- H116 pistons,Scat I beam rods, 60403 Voodoo cam, ede 63cc heads, ede air gap intake,MSD 6AL box,Accel distributor 16 initial 34 total,750 Holley 4779, Dougs d453's, Rostra 250-1223 cruise control.

14MPG is the best I've been able to muster this year.

The 22 was real with my 68 Cuda. I was very impressed. The car had no P.S. weighed 3200lbs, Barracuda is a pretty slick shape and the TQ and headers all contributed I think. I know how to tune car as well and it was properly jetted and had a proper advance curve in it. Also the manual trans doesn't slip like a tork convertor does.
My Viper gets the same fuel mileage with it's 514 but uses all these tricks plus over gearing to achieve the same results.

I never really felt a need to check the mileage on any of my performance cars. Even when I was a kid I just drove it an filled up when needed.

Sure that wasn't Km's?
Don't want to be a d*ck, but with 14" tires and 70mph, what was the RPMs, 4000?
I applaud you, must have had a super tune.

Nope it wasn't kms. It was getting 26MPG but that was imperial gallons, converting to US gallons comes out to 22. It actually shocked me as I expected it to be more like 15 or 16 MPG US. The plugs were not white either. They were a light tan. I believe it was running on the primaries but you are dead on it was taching a lot higher than I would have thought would have made good MPG.
I don't believe it could have made better MPG with a 2.76 either, so maybe it was a sweet spot for the camshaft.
2900RPM is what the calculator comes up with at 70MPH for 3.23 and 225X70X14.

1968 GTS convertible 340/727/3.23 open with 215/70/14 tires.
Back in the 1980s I used to get about 17. In later years about 15. I suspect that was due to the posted speed limits and not exceeding them by a great deal...

Years ago I had a 72 Duster 340 4 speed. 3.91 gears. MP purple shaft 284* 474 lift cam. With TQ it got 21 mpg. Tried a 6 pack and only dropped to 20 mpg. Same thought as a post above. Jetting and advance curve took lots of experimenting to find best tune.

You bring up a good point, all these great numbers are from "years ago".
Gas is much worse today. I have Fitech so I'm confident the A/F is right.
The difference is my timing is limited to maybe 26 to run 89 and keep it from pinging in the 90+weather.

Still don't see how I'd pick up another 6mpg, that's almost a 50% improvement.
Looking at the majority of the responses, disregarding the "back in the days", it looks like 12-15 is all you can expect.

I'm the only guy on this thread that ran a TQ. It was a great carb but you won't find one in good shape these days. I imagine if I had run a square bore carb of some sort it would have cost fuel mileage dearly.

As stated above, I ran a TQ before trying the 6 pack. Tried smaller Jets and lots of different metering rods to get to 21 mpg. I only switched to the 6 pack to see if I could get the same mpg and a little better performance. I really liked tuning that TQ.

Year and car model - 70 Swinger
transmission - 727
rear gear ratio 3.23
tire size 205 70 14
average highway speed 65-70
any modifications from stock 30 over stock rebuild, HE 268 cam, AVS from a 68 383

18 - 20 mpg at 65 mph on many I-95 trips up and down the coast.