Yeah, the car runs great so I'm with you guys on thinking it's engine temp related.

First it was oil coolers, now it's going to be engine block heaters...LOL

No, don't mix the gasolines, go to a different Shell station.

I have two shell stations within two blocks of each other. I gave up on one because it was disgusting and the pumps were always out of order. The other seems to be better run and is where I've been filling up. My guess is it's not the gas...or both stations get replenished by the same trucks.

The computer on the 370Z for gas mileage is by far the best I have had in a car. It has been accurate to within .1 of a mile for each fill-up I have calculated.

Try to fill up with Shell, different brands of gasolines could have different volitile levels. It's not bad to mix them, but your engine may run a little different.

Had same problem as you, my commute to work is ~9 miles, half city half highway - my mpg is ~16. I have been trying different brands and I get the best mileage on chevron/shell, worst on 7/11 gas.

For me it completely depends on how I drive. I can get 28 MPG even on a hilly highway but I typically get 16 MPG with my foot on the throttle and its not the speeding - I really try to keep it within the limit as the cops are just crawling all over the place lately. Its the quick accelleration that gulps the gas.... which explains the 13 MPG I've gotten in the past ;)

Something else to remember is to at least allow 2,000 to 3,000 miles to allow all the parts to break in and seat before calculating the MPG. I change my oil and filter w/ Mobil 1 5W30 at 1,000 miles in all my cars to remove any flakes/dust/etc that comes off in the beginning of the break-in process. I then change the oil/filter at 5,000 miles and every 5,000 miles thereafter also with Mobil 1 5W30.

I am sorry to hear you mileage is less than many are getting. I have owned my z for 6000 miles and the worst MPG on an entire tank was 20.4 and the best is 22.9. Those numbers are all in town driving approx 50 miles a day. On the highway I've gotten about 26MPG but is has been a while since I have taken it on the highway.

P.S. I am a very sporty driver. rarely baby the car!

i have tested the trip computer multiple times it is pretty darn acurate, infact its acurate enough i dont have to test it the old fashion way any more.

WOW you change your oil every 5k and not 3k? do you use synthetic?

I always change my oil at 5000mi with synthetic. Whatever you think, but 3K is overkill with synthetic, IMO.

I have averaged as low as 19mpg with some very aggressive driving. But the 370Z can be a very fuel economic car. I live in a somewhat rural area, so 80% of driving is technically highway driving. Not much stop and go around here and its only for brief periods of time when it is.

I just filled up today and averaged 28.1mpg (507mi on the tank and 18gal & tripmeter said 27.7mpg). On an 8-hr round trip, I averaged 29.2mpg c A/C blasting all the way. Of course, I had a little careless accident a week ago and have and will continue to drive like a little granny. I upshift @ 1500-2000rpms on every shift. Utilizing that low-end torque and keeping your R foot off the floor is a great way to save fuel!!

Short trips and frequent cold starts are about the worst thing for fuel economy, also. Doesn't matter how much you baby the car...fuel enrichment when the engine is under operating temp REALLY sucks the fuel down.

Late,
Trav

Yes I use Mobil 1 synthetic and change my oil and filter every 5,000 miles. To me doing it every 3,000 miles is over kill unless I am using a regular dyno oil.