Suburban vs. Impala (or similar) fuel economy?

[66Submarine]

Been thinking about this recently; I have the HD/WTF truck thing well covered with my one ton truck(s), so another thing I'd be driving really wouldn't necessarily need to do that.

So, I've been considering something like an old four door Impala vs. a Suburban; certainly seems like the car would be a lot more aerodynamic and get much better fuel economy rolling down the highway in the hammer lane than the Suburban would.

I know most of the time something like this comes up some guy with a sunk carb float likes to talk about how every car/truck from the 60's gets 5MPG or something stupid, but does anyone have any real input? Seems like the immensely sleeker car would have to net me some noticeable gains over the much more brick-like trucks/'burbs.

[Lugnutz65]

I can't tell you what kind of MPG a Burb or an Impala will get.
I drive a 66 Ford Galaxie 500 with a 289ci honed 30 over and get at least 14 MPG. For comparison, my Galaxie is the largest car FORD made in 1966. It's at least the size of the Impala that year. I'm hoping that my newly installed distributor will give me better than 14 MPG. The 14 MPG was when I had a distributor with a wobbly shaft.

I think your hunch is correct and the Impala will get better MPG than any Burb.

[LVPhotos]

Overdrive! High gears and weight have alot to do with with MPG. Trucks with a 3:08 gear will get better MPG than one with 3:73 or 4:11. Impala is not a light car but geared for driving not towing as were the trucks. Engine torque will help get things rolling faster. So look at power to weight as well. I still can pull 20mpg with od in my short bed.

[Lugnutz65]

Originally Posted by Lugnutz65

I can't tell you what kind of MPG a Burb or an Impala will get.
I drive a 66 Ford Galaxie 500 with a 289ci honed 30 over and get at least 14 MPG. For comparison, my Galaxie is the largest car FORD made in 1966. It's at least the size of the Impala that year. I'm hoping that my newly installed distributor will give me better than 14 MPG. The 14 MPG was when I had a distributor with a wobbly shaft.

I think your hunch is correct and the Impala will get better MPG than any Burb.

Adding to what I said earlier . . . my Galaxie has a 3.00 rear diff. Nice for cruising but not very fun at the light or off the line.

[66Submarine]

Yeah, my idea is that if I can get close to 20 with a half ton truck without much trouble, I could probably get over 20 with the more aerodynamic car (and/or drive much faster).

The '68 more-door I'm looking at is slightly lighter than a Suburban (about the same) and should have 3.08 gears, so I think it should make a pretty nice low-budget cruiser platform.

[NEWFISHER]

50 Burb. Built 250 (everthing you can throw at one internally ...Holley 390/cast headers), 700r4, 3:73 29" tire 19mpg at 55 ish

[66Submarine]

Originally Posted by NEWFISHER

50 Burb. Built 250 (everthing you can throw at one internally ...Holley 390/cast headers), 700r4, 3:73 29" tire 19mpg at 55 ish

Only 19 from that combo going 55MPH? Huh. Lots of real steep hills, maybe? When my father was driving my '65 C10 locomotivated by a shot-out 250 with 3.73 gears and a three speed (30.5" tall tire) the truck got 17-20MPG and seemed to average something like 18MPG most of the time.

[Clyde65]

SWB 65, 4.8/4l60e with 3.73, I get 19.5 with 75-80% highway.

I think you should get what you want and then make it yours.

[NEWFISHER]

It also does cool low gear burnouts and hauls a 3000 lb 20' camp trailer

[66Submarine]

Originally Posted by Clyde65

SWB 65, 4.8/4l60e with 3.73, I get 19.5 with 75-80% highway.

I think you should get what you want and then make it yours.

Well, I like both of them for different reasons. Seeing that I already really have the "truck" thing covered several times over, I'm thinking an actual car may be somewhat predisposed at being better at the whole "car" thing.

The fact that the old four door cars are still cheap and easy to find makes it even more enticing.

Originally Posted by NEWFISHER

It also does cool low gear burnouts and hauls a 3000 lb 20' camp trailer

19MPG is pretty good if you are getting that doing burnouts and pulling a trailer.

[Lugnutz65]

Originally Posted by 66Submarine

Only 19 from that combo going 55MPH? Huh. Lots of real steep hills, maybe? When my father was driving my '65 C10 locomotivated by a shot-out 250 with 3.73 gears and a three speed (30.5" tall tire) the truck got 17-20MPG and seemed to average something like 18MPG most of the time.

Please allow me to make a comment about calculation of MPG. I'm not saying anyone here is calculating it wrong. But then again, they might not see that their method is potentially flawed.

In the example above, I presume that with a taller tire, the actual odometer reading (mileage) was re-calculated due to the fact that taller tires will throw off the accuracy of the true mileage driven.

Two things MUST be accurate for the MPG calculations to be valid. Exact amount of FUEL and exact mileage. But all too often, we mess one of those up (or both).

Examples of inaccurate calculation of mileage: I have a small 4 cylinder Nissan RWD truck. I have slightly bigger tires on it than the factory installed. Using a GPS, I have figured out that my speed is off by 5%. So 50 MPH is really 52.5 MPH and 60 is really 63 MPH and so on.
Take home message = different tire sizes will make your speedometer inaccurate and throw off the calculated MPG at the pump.

Another example: I recently drove my old FORD classic on the highway for a 4 hour trip. I wasn't sure if my speedometer was accurate so I started counting mile markers. I found out that mile markers on the highway are not spread out at exactly 1 mile. Pretty close, but not close enough to be accurate for exactly 1 mile.
Take home message = If you use an aftermarket programmable speedometer - the kind that has you press a button and then drive exactly 1 mile and then press the button again to set the speedometer - well, it might not be as accurate as you think if you used a mile marker on the highway.

About calculating the amount of fuel used - Most of us calculate it at the pump. Hopefully we don't use the gas gauge on the dash.

I'm reminded of a Mythbusters episode. They used a fuel cell and calculated exactly how much fuel they used by weighing the fuel cell. Weight change was equal to amount of fuel consumed. Just that simple. Very accurate but I certainly can't do it that way.

Most of us calculate MPG at the pump. We see how many miles we went since the last fill up. Then use simple division to calculate MPG. Then we hit the trip meter on the dash and click off the miles until the next fill up. However, errors can be made using this method. Still . . . it's about the best I can come up with and stay practical.

Examples of potentially inaccurate fuel calculation:
All of these will cause only a small mistake in calculating fuel use.
1. Using the dash gauge is highly inaccurate. Too often folks think that when the gauge is at the half mark that they have used 1/2 the tank. Rarely true.
2. Filling the tank using a different pump. The different pump may have a different shut off pressure and may not fill up the tank the same.
3. At a different pump, the tank may fill differently due to truck sitting at a different angle.
4. The last person who filled up didn't top it off the same way you do.

Having said all this, what is best? First, make sure you have a way to accurately calculate mileage. You must verify that your odometer is accurate and if not, then what percent is it off by? I suggest that you follow someone with a modern vehicle that has factory installed tires. Measure at least 10 or 20 miles by their odometer and see what yours shows. If possible, use a GPS to confirm the distance. That should give you a way to mathematically calculate your true mileage in the future.

For fuel, calculate the MPG by using the combined gallons from 3 or 4 fill ups. The small variances will average out.

After reading my words above - I see how truly dull and boring I can be. So I'm gonna go to bed.

[66LSx]

EITHER WAY!!!!
LS swap FTW! EFI, selectable tow haul mode, easy starts, overdrive.... EXCELLENT MPG! (pending right foot behavior)
(2005 Silveardo 5.3L LM7 / 4L60e)

[NEWFISHER]

^^^^^^ winner!!!

[66Submarine]

Originally Posted by Lugnutz65

Please allow me to make a comment about calculation of MPG. I'm not saying anyone here is calculating it wrong. But then again, they might not see that their method is potentially flawed.

Yeah, I get that. I personally used map mileage and weighed the fuel needed to bring the level back up to a height I measured with a dipstick to get those numbers.

Originally Posted by 66LSx

EITHER WAY!!!!
LS swap FTW! EFI, selectable tow haul mode, easy starts, overdrive.... EXCELLENT MPG! (pending right foot behavior)
(2005 Silveardo 5.3L LM7 / 4L60e)

Uhh...I'm the guy that bought the $400 6.0L LQ4 the other day, remember? They are certainly very neat engines. Not a big 4L60E autotragic fan/supporter, though.

[66LSx]

Originally Posted by 66Submarine

Uhh...I'm the guy that bought the $400 6.0L LQ4 the other day, remember? They are certainly very neat engines. Not a big 4L60E autotragic fan/supporter, though.

Unfortunately your 6.0L isn't a sipper like its smaller siblings in the MPG department (which was your original target topic).

The 4L60e does the job of a stock 4.8 and 5.3L especially when its in a truck with no weight/traction.

4L60e > 700R4.... which would be the other auto trans for MPG.

4L80e while larger also yields the lower MPG for more rotating mass.

4.8L Vortec / 4L60e in a burb or impala would yield nice mileage and you then then use 3.73 gearsets and not get butthurt in the city MPG like you would would 3.08's

4.8L and a T5 would be good too for MPG. (Again this wasn't a high horsepower build)

I'm expecting my 5.3L / 4L60e setup in the 66 C10 (stock) with simple long tubes/h-pipe to flirt with that mid 20's number. (If it can do low 20's in a crewcab 4x4 @ 5500#.... I should have no problem remaining/gaining MPG with 2000 lbs lighter). (Even given the garbage aero)

[66Submarine]

Originally Posted by 66LSx

Unfortunately your 6.0L isn't a sipper like its smaller siblings in the MPG department (which was your original target topic).

The 4L60e does the job of a stock 4.8 and 5.3L especially when its in a truck with no weight/traction.

4L60e > 700R4.... which would be the other auto trans for MPG.

4L80e while larger also yields the lower MPG for more rotating mass.

4.8L Vortec / 4L60e in a burb or impala would yield nice mileage and you then then use 3.73 gearsets and not get butthurt in the city MPG like you would would 3.08's

4.8L and a T5 would be good too for MPG. (Again this wasn't a high horsepower build)

I'm expecting my 5.3L / 4L60e setup in the 66 C10 (stock) with simple long tubes/h-pipe to flirt with that mid 20's number. (If it can do low 20's in a crewcab 4x4 @ 5500#.... I should have no problem remaining/gaining MPG with 2000 lbs lighter). (Even given the garbage aero)

My point was that I'm well aware of the LSx series--the fact I just bought one would seem to indicate that, ya know? Also, my OP wasn't really about maximum fuel economy--it was/is about the relative fuel economy of the more aerodynamic car vs. the trucks.

Not really much of an auto fan in general; I personally like that extra pedal to the left. The 4L60E (and 700R4, for that matter) is pretty well known as a problematic/weak/short-lived transmission (at least in stock form). I might stick an old TH400 in something if I just want to act stupid (drag racing), but other than that the autos don't really do much for me.

[66LSx]

Originally Posted by 66Submarine

My point was that I'm well aware of the LSx series--the fact I just bought one would seem to indicate that, ya know? Also, my OP wasn't really about maximum fuel economy--it was/is about the relative fuel economy of the more aerodynamic car vs. the trucks.

Not really much of an auto fan in general; I personally like that extra pedal to the left. The 4L60E (and 700R4, for that matter) is pretty well known as a problematic/weak/short-lived transmission (at least in stock form). I might stick an old TH400 in something if I just want to act stupid (drag racing), but other than that the autos don't really do much for me.

I assumed from your 6.0 thread post you bought it because of the deal and it was a 6.0. (not MPG capable) [was was the title 'what a deal!']

When I read (Suburban vs. Impala (or similar) fuel economy?) I assume were discussing fuel economy as most of these cars don't have original motors.

Aero to aero.... same motor and rear gear set... impala wins 10 out of 10 times


By your last post I'm assuming your talking suburban vs. impala with OEM motors, trans and rear gears then.

If that is the case.... suburban will have some input and probably impala will be the wrong forum or only a response or two from actual impala owners.

It'll be a wash as the impala has twice the weight.. twice the aero.. truck is half as heavy but just a boat sail.

Maybe consider a diesel swap otherwise if your chasing real MPG. (cummins 4BT, 4BD1/2T isuzu etc. if you want 30+ mpg)

Good luck to your endeavors of a 4 door impala vs. suburban. Hopefully you figure out what you really want it for... as impala is passengers and a big/short trunk... burb is tall cargo that can carry passengers on occasion.[a YOU decision]

[66Submarine]

Originally Posted by 66LSx

I assumed from your 6.0 thread post you bought it because of the deal and it was a 6.0. (not MPG capable) [was was the title 'what a deal!']

Yes, I bought it because it was a very desirable 6.0 for a great deal. But If I know about 6.0's I probably know about 5.3's too, right? Not that much of a stretch.

When I read (Suburban vs. Impala (or similar) fuel economy?) I assume were discussing fuel economy as most of these cars don't have original motors.

Yes, Suburban vs. Impala fuel economy. Key words: Suburban vs. Impala.

Aero to aero.... same motor and rear gear set... impala wins 10 out of 10 times

I could also put smaller mirrors on my truck and win 10/10 (by a small margin) over the slightly larger mirrors. The question is/was by how much?

By your last post I'm assuming your talking suburban vs. impala with OEM motors, trans and rear gears then.

No, not really. Both use the same engines/transmissions, and the same swapping and rear gear swapping is common. Equal playing field as far as I'm concerned.

If that is the case.... suburban will have some input and probably impala will be the wrong forum or only a response or two from actual impala owners.

Most people on this forum have probably had more than one car/truck, or at least know someone who does. Might I add:

Totally redesigned in 1965, the Impala set an all-time industry annual sales record of more than 1 million units in the U.S., which has never been bettered.

That doesn't really sound like a super obscure car, does it? A LOT of people have had them. If you want the generic GM "family car" to go with your 60-66 truck, that's it. I didn't even say it had to be an Impala.

It'll be a wash as the impala has twice the weight.. twice the aero.. truck is half as heavy but just a boat sail.

Nope, not even close. A '68 four door Impala is actually slightly lighter than a '60-'66 Suburban, and just slightly heavier (if any) than a LWB truck.

Maybe consider a diesel swap otherwise if your chasing real MPG. (cummins 4BT, 4BD1/2T isuzu etc. if you want 30+ mpg)

Diesel swaps are very expensive and have drawbacks. I think it would be neat to do one, but I can't really justify it from a monetary/practical perspective (at least at this time). Also, this is again not really related to the question.

Good luck to your endeavors of a 4 door impala vs. suburban. Hopefully you figure out what you really want it for... as impala is passengers and a big/short trunk... burb is tall cargo that can carry passengers on occasion.[a YOU decision]

Realistically speaking, most of us here probably do not need/use the capacity of a truck most of the time. I can use my WTF HD one ton truck when I want to drag logs through the mud, pull houses, or haul a pile of BBC's in the bed. The rest of the time the big car would be great--especially if the fuel economy was better when you want to drive 500 miles running 80MPH. The Suburban has a little more seating or cargo capacity, but do I really need that? Not really.

It was just a harmless question. I guess I should have saved the space for another valuable and interesting thread asking if you can put a 350 in one of these trucks, or something like that...

[NEWFISHER]

Dibs on your 4l60e trans

[66Submarine]

Originally Posted by NEWFISHER

Dibs on your 4l60e trans

I don't have any, but I will gladly come up with one blown up 4l60e to give you for every 4/5 speed manual you give me.