eicca

I consistently get ~30mpg when I do the following: set the cruise set between 70-75mph, making engine RPM 2200-2500, and avoid speeding up or slowing down. Small inclines don't seem to have an effect on said average as long as engine RPM remains constant. If I pass other cars, or go over 80mph, gas mileage average plummets to ~22mpg.

It makes sense to me that an engine would have a sweet spot in the RPM range where it tends to "self sustain" and its own mass facilitates its rotation, requiring less fuel. I know when I'm riding my bike, I have a pedaling speed where the mass of my legs does more of the work than my muscles and helps me maintain speed with minimal effort.

Thoughts, all you experts?

AmanO

How dry is the air where you are and what are average temps when you do this?

I cannot even start to ask about the speeding up and slowing down, as people where I live missed the class explaining the passing lane.

eicca

Yeah, maintaining a constant speed is somewhat difficult here as well for the same reasons.

I've achieved 30mpg in both warm and cold, medium humidity.

firelizard

iTrader: (1)

I haven't been particularly precise but yeah, I've noticed the 3UZ is really comfortable at highway speeds and I can usually maintain 9-10L/100km as long as it's not winter. Not bad compared to the atrocious city driving fuel consumption. It's clear that the GS is meant to excel at longer drives, outside of traffic.

FrankT

On my GS400 pushing 300,000 miles, I am thrilled to report; my 1500 mile round trip to Northern New Mexico and back last summer, my MPG was 26-28 per tank traveling between 70-80 MPH. I probably could have done better but at times, passing traffic, I would speed up to 90+

Smooth V8 and a excellent aerodynamic qualities help out with those results...
...but city driving gets me in the mid teens for MPG.

1QWKGS4

iTrader: (3)

I've owned my GS400 for almost 22 years.. Seems like a century ago.. lol

But what you said is achievable. I've gotten 28-29 mpg hwy crusing around 75 mph in high humidity in the southern states and anything 80 and above and it plummets to 22 mpg exactly as you said.
(it is hard maintaining that slow of a speed as the car just begs to be pushed to around 80-90mph, it seems to be its sweets spot for hwy cruising..)

1QWKGS4

iTrader: (3)

My 2GS GS430, same bodystyle. No matter what I do. It can never get above 25mpg on hwy.. maybe the additional .3 liters is the downfall but GS430 is more torquey engine. It has better all-around (more usuable power) with the same Horespower but feels much stronger.

eicca

My uncle has a 430 and says the same thing.