Road Trip

[lloyd3]

Made a new friend last summer who lives down in Colorado Springs. He's 80 now, but he was a very serious car guy for many years (owned them, raced them, etc.). He and I also share an interest in old English double shotguns and bird hunting. Long story short, he's a transplant from Calli(fornia!) and he's clearly casting about for like-minded folks (ie, "friends"). I'm a transplant here too (except I've been out here for 40-years now).  Anyway, we had chatted about going to lunch someday in my old car several times and yesterday was finally it. 

The mountain you see in the distance is Pike's Peak. The weather was nearly perfect, slightly cool and very dry.





Gives one a sense of the scale of things out here, eh?  If you live back East (or even in California) this should give you an understanding of how things used to look out here (before Colorado's bigger cities essentially became California). 

Before this trip, I specifically made sure I had enough fuel on-board because between our two homes there is only 1 convenient gas station (& where I topped-off first), 7mpg and 19 gallons tends to really keep you focused on the subject.  FWIW: lunch was nice and the owner of the little breakfast shop we went to turned out to be yet another car nut. She made it a point to track us down to ask me about what was sitting in her parking lot. She only knew enough to be interested, but she was pleasant and asked good questions (you never see 2nd generation cars out here anymore, not sure why).

The car ran surprisingly well and with no issues (it's sadly become an act of faith for me anymore, because I never take it anywhere far from home) and it's on roads like this where you really wish you had another gear to use (or maybe even an automatic and 3:23 gears).  As it was, this "secondary road" speed limit is only 60 mph and at roughly 3,300 RPM that's about what this car does comfortably over long distances.

I think I'm going to be doing more of this.

[Kern Dog]

Good for you, Lloyd.
I'm always surprised to read of the mileage that you report. 7 seems really low for a fairly stock car on street axle gearing. The lack of overdrive will limit freeway mileage but 7 ?
I am on the finishing touches of a roller cam swap in my car and contemplating the annual 900 mile road trip with it!

[lloyd3]

KD: It might even make 8 mpg on the highway but not much more. No matter, that's not why I own it.

Out of curiosity, what is the average for one of these cars in a "stock" configuration?  I know the automatics are a little better and then a more-standard highway gearing (3:23) helps even more. I'm guessing 12-14 mpg on such a configuration but I can't imagine too-much better than that for a 2nd generation R/T car?

I'm guessing the combination of the 18-spline 4-gear and the 3:54 Dana is the issue here, the carb is the factory 4428s Carter AVS.  These cars were never built for fuel efficiency (gas in 1968 was what exactly, something like .29 cents per gallon(?) and this is perhaps why the 4-gear Chargers only account for like 10% of production (the 130 mile range on a full tank does suck just a little).

Nobody cared about fuel costs then.

I might add here that my newer (2017) Toyota Sequoia is actually making more-like 15 mpg now (I figured out how to use the fuel economy calculator in the monitoring system) and that is better than the 12 mpg that I had originally figured-on, but not much. 

Bigger cars (and bigger V-8s) aren't known for their fuel efficiency. I can always buy another Honda Civic if that becomes an issue again (but I'm guessing it won't for me). 

Maybe I'll even go "electric" someday (just don't hold your breath).

[Kern Dog]

The 3.54 Dana is not a light axle, the energy to spin that dude is certainly higher than a 3.55 8 3/4" axle so that is one factor.
Looking at old road tests from the late 60s, they reported freeway mpgs in the 12-14 range with the standard 3.23 R/T models so a number of 8 is just not in line.
I look at your number and wonder why I have such a huge difference since I have almost 495 cubes, a bigger cam, an 850 carburetor and mine probably weighs a little more. The wider tires would seem to be detrimental to mileage too. Last year with a bigger cam and driving faster, I was in the high 12s on the freeway but then my overdrive cuts my 3.55 down to around 2.27. That is a huge difference right there. I got 15.1 back in 2022 with the same engine size, same gearing but before the engine rebuild. That mill had a smaller, milder cam.
I know, we don't drive these for the economy and forgive me for dwelling on it. I do think that for some, poor mileage can be the difference between wanting to casually drive around in a classic or to just drive a later model car.

[Mike DC]

 
Other mileage factors:

- Bias-ply tires cost fuel.  The OEMs switched to radials in the 1970s because of the gas crisis.

- Ethanol reduces efficiency.  Pure ethanol only makes 2/3rds the power of pure gas.   

- Kanye West.  Don't tell me he's innocent in this. 

[70 sublime]

My old 69 Charger with a 383 in it got 20 mpg on my last road trip doing 70 mph for 3 hours straight
The car had 2.92 gears in the back which totally sucked in town but was great out on the open road

[Mike DC]

 

My old 69 Charger with a 383 in it got 20 mpg on my last road trip doing 70 mph for 3 hours straight
The car had 2.92 gears in the back which totally sucked in town but was great out on the open road

20 mpg is good for a 383, even with tall gears.  Was it a stick tranny or a 2-barrel carb? 

I've heard of pretty good numbers using 1980s truck 4spds in muscle cars.  That was the hot ticket for overdrive before the Tremec trannys.

[70 sublime]

My old 69 Charger with a 383 in it got 20 mpg on my last road trip doing 70 mph for 3 hours straight
The car had 2.92 gears in the back which totally sucked in town but was great out on the open road

20 mpg is good for a 383, even with tall gears.  Was it a stick tranny or a 2-barrel carb? 

I've heard of pretty good numbers using 1980s truck 4spds in muscle cars.  That was the hot ticket for overdrive before the Tremec trannys.

Auto and 2-barrel

[Mike DC]

Auto and 2-barrel

So it was a non-Magnum 383?  I think those had smaller cams than 383/440 Mag.  That would help mileage a bit.

I assume it had radial tires too? 

[lloyd3]

Yeah, the 2 383 mags I owned were never close to that. The 70 RR was an auto and it got maybe 16? The 4-gear 70 Bee was 14 all day, much less if you pushed it (& I pushed all the time). I believe both were 3.23s.

I've never owned a fuel-efficient big block.

Edit to add:  Just for kicks, I used Google AI (artificial intelligence) to look up "fuel efficiency of a 70 roadrunner". "8 to 13 mpg" was the answer, depending on how it was equipped and how it was driven.

They did mention that some owners reported up to 17 mpg "during steady highway cruising at lower speeds". I'm assuming 383 auto for this one.

[timmycharger]

Fuel economy is probably the least of my concerns with my Charger however I read that if I really tried, I could get decent mileage from my 440 six pack if I keep my foot out of it and not open the outboards.

I will probably never know as it is virtually impossible for me to drive that way