i just got 395 miles for 16.5 gallons of 80% highway driving at average speeds of 90 mph.

i never do highway driving so i was curious about what i would get this time and i got 23.5 mph which i find poor-average.

i've got:

Brand new 300zx z32 fuel filter (not even 2k miles old)

first time mobile 1 supersyn 10w30 motor oil (i just switched like 2 weeks ago. all highway driving done was on this oil)

Injen cold air intake (5k miles on the filter)
16" stock rims with 40 psi pressure.
Shell 91 octane gas

auto tranny with 39k miles on engine
and i was the only person in car.

i dont know what else i should do to improve my gas mileage. i know alot of people post MPG threads but i need to know what i could possibly do to improve it.

my only performance mods are INJEN CAI and warpspeed y pipe.
i do feel a great loss of power in the low end but i think thats cuz of the y pipe. could it be the KS? (i cant check for codes cuz my ECU is messed up, the screw never goes against a stop, it keeps turning and turning and turning)

BTW: i do know that i need a balacing, could balancing mess up mpg??

i would like to know what kinda mileage other folks get doing highway driving only.

 

I do lots of trips between the bay area and Lake Tahoe and if I drive normally (~75-80 mph) I get about 27-28 mpg. On one trip I forced myself to drive slow, I set the cruise at 63 (verified with GPS) and I had filled up in Auburn, drove 162 miles home and topped off with 3.975 gallons and got nearly 41 mpg! So when you read that slowing down increases mileage dramatically, they ain't kidding. Not that I'm going to slow down much though...
BTW, I'm auto and the long overdrive gearing helps, that's why the auto was rated one mpg better hwy than the 5-speed.

 

I get about 360 hwy. I use Shell 93 octane and I drive pretty fast. I'll usually set my CC at 80mph...but I'll mess around w/ other cars if I see them...(goin up to 110 or so)

 

Just came back from Fl. One time I filled up after averaging 70-80mph and got 28.2 mph. I have a 99 5-speed with 93k miles. Problem is I can't keep the speed down below 70.

 

haha we average around 16.5mpg(20 canadian mpg) in a 98 maxima se auto. were all still trying to find out why it is so bad it just got a 5000 rebuild because of a BHG and since then we have seem to be gettin sh*t gas milage but we do a faire amount of city driving. we always use 91, 92 or 94 octane. This isnt really related to this post but is it true canadian gas is better than american gas or is it the other way around

 

Cruising at 70 - 75 mph I get 29mpg.

Around town, I get 24.

 

I get 26mpg, mostly highway with an automatic. About 110/day on the interstate and 10-15 in town. Cruise is set at 78, but many times I'm crusing at 85 on the way home (no rush to work) with occasional blasts faster.

Right now I have 199,500 miles, easily hit 200k this week.

 

I can routinely get the equivalent of US 28 mpg on a highway trip and have had as much as 31. I generally run 89 octane, but am running Chevron 92 right now.

I am told that Canadian gas has more additives than US gas and if an American car that is used to running 87 octane runs with Canadian 87 octane they notice an improvement. When I do fill up in Blaine (across the line) I generally by high test, whatever is available but not 94.

It strikes me that one can't b!itch about gas mileage when averaging 90 mph. Optimum mileage would probably be achieved at about 60 mph and you would certainly notice an improvement if you averaged 70, rather than 90 and burst up to 110. What do you expect? Also, not sure what 40 psi in your tires will do for you, that sounds a bit much to me. Maybe go down to 35. I run 33 front, 32 rear on the highway and mine is an SE with a stiffer suspension, albeit stock.

 

does anyone know what speed on highway gives u the BEST MPG for the automax???

 

Woo Hoo! Another thread about gas mileage.