With all the recent talks of fuel economy and what people are seeing on average with their various generation LS4's I wanted to know what I could get out of mine.

I do a lot of driving for a living. Mostly to and from production locations. My company needed a bunch of camera gear serviced up in Chicago and instead of paying a large sum of money to ship and insure the gear I drove it up.

The quick and dirty is the following.

1995 LS400 w/65k miles currently.

Filled up before I left at a BP in Indianapolis. I used mid grade 89.

I made it to Chicago and began my trip back. Right outside Indianapolis I stopped to fill up (gas is cheaper outside the city).

I had traveled 415.8 miles and filled up -- again with BP 89 -- 13.923 gallons.

I was shocked when I did the calculation. It came out to 29.864 MPG on that trip!

Needless to say I was quite happy. Granted, some will argue my calculations were not 100% scientific --- I know. There are probably many variables, but on this trip, at this time, I was quite happy.

I can only attest to the following.

1. New NGK plugs and wires about 2k miles ago.
2. Full Seafoam treatment
3. Injector cleaner in tank.
4. Full Synthetic Mobile One 5w30 in the engine.
5. Full Synthetic Royal Purple in the rear diff.
6. Aired the tires to 38 PSI
5. Drove exactly 68 MPH (GPS) with the AC on and off at various times.
6. Light on the throttle.
7. I65 from Indy to Chicago is perfectly flat.

Anyway, just had to share.

 

Great job.. You had alot of conditions in place to achieve such a 'mpg' figure.

1st gen's have gotten 30, I've gotten 30 for sections of times, but the overall avg is generally mid 20's.

I would say this.,.. all LS's get reasonable gas mileage, some great gas mileage.

The 2nd Gen engine is more efficient than the 1st. Not so much so that is makes the 1st Gen pail in comparison but, it is seemingly more fuel efficient.

The whole key to this economy, is the throttle Like yesterday I drove about 75 Miles.. Needle didn't move a notch, cranked it up today, exact same spot. Have 224 Miles on this tank so far and it is just under the 3/4 mark. I am very happy with these figures --

One other thing I am noticing though.. I am driving ALOT more than I used to , now owning an LS.

 

Yes, I agree. I've been very happy with the economy of the LS4.

My other car is a 2005 Pontiac GTO. With a 6-speed I can actually push about 28 MPG on the highway. Again, speed is the key. Crank it up to 80mph and the MPG drops very quickly.

Now, drop the hammer and the instant readout shows about, ummmm 1MPG and sometimes 0. But thats what 6 liters and 400hp does.

So my two V8's --- if driven correctly --- get about the same mileage as some 4 and 6 cylinder engines.

 

That is an impressive number - I drive around 80 miles round trip to the office and rarely exceed 26 mpg (207,000 miles).

 

I get killed on mpg because I live 3 miles from the office, stop and go, car doesn't even have time to warm up. I'm lucky to get 15mpg around town.
I can get closer to 25-27 on cruise control on highway, but it's so hilly around here it jumps around alot.

 

On the flip side though, you only have to drive 6 miles round trip on your commute. Your saving even though the engine isn't running as efficiently as it could be =)