to see the pressure readings in the intake manifold that I would want to see yes....BUT if you know a way to see 8-12psi in the intake manifold without FI PLEASE pm me and let me know

 

I recently got 18mpg, which is my best so far. Probably 70% freeway, never exceeding 80mph. 73-75mph cruising. I keep it at 3k cruising around town, shift at 4k.

MAYBE my mileage will increase when I finally take nonstop freeway trips..?

 

^if you keep the rpm's under 3750 you'll see around 22 or so (as long as there is not other problems with the car....well that's waht i get anyhow)

 

Yeah, I try not to go over 75mph, because that's starting to pass 4k RPM. Again, I've never driven strictly freeway and filled up right after, so all my results thus far have been spoiled by my city driving. I will try shifting before 4 around town, but the lack of torque makes it difficult to do smoothly, especially 1-2.

 

I'm in AZ so I don't think that I can avoid ethanol for half the year. I think all places here are ethanol 1/2 the year and MTBE 1/2 the year. How much does ethanol affect mpg, and does MTBE alter the mpg?

 

I got around 24mpg with 3 people (including me) and full of baggage. I went from Montreal to Toronto so it was nice It was practically 98% Highway and kept at 70mph average.

 

Not too much, maybe only 2-3%. Some people have claimed more of an effect, some less.

 

Oh so that was you! I actually first read that claim a few years ago and did not remember who posted it. I've thought about seeing what was possible below 65 mph but have not been able to bring myself to actually do it. Even if I could, In the NE, I'd probably get shot by road rageaholics.

 

I wanted a sports car
I bought one
I drive it like a sports car
I expect it to consume fuel like a sports car
I expect to pay for said fuel consumption

I went through a tank of gas in the two days after I got it... 16mpg, mostly highway

Maybe I don't really care because it's not my DD...

 

11 km\l with 40% highway 60% country roads mostly in 6gears. average speed was around 120km\h.
Maybe we have better gas here? My rx8 is not stock but is still NA

 

Highway driving is hardly the best use of a sports car. For me, and I think others in this thread, I'm only interested in knowing what the car is capable of under ideal conditions as a matter of intellectual curiosity. But it also may be politically useful to to say that I can get up to 28 mpg on the highway when my in-laws start making remarks about this or that aspect of my car purchases. If anyone here wanted maximum fuel economy, they would buy another car. But the RX-8 is pretty good for me as a daily driver because I have a rather short 'mountain'-road commute that is perfect for my sports cars. If I had a long highway commute, I probably would make a different choice for a DD.

 

Hahaha when I said most of it was highway driving in those first two days I meant I was driving it home from where I picked it up... I already stated it's not my DD because my commute is 95% highway driving. I have a Ninja 250 that gets ~60 mpg for that trip. When I take the 8 on the highway it's to find relatively empty parts (aka the only person I'm going to hurt is myself) and take on-ramps/off-ramps-bypasses at higher-than-posted speeds.

And I hope that in-laws story was hypothetical. If I ever have to defend my purchases to anyone with reasons other than "because I wanted to" than I'll feel a need to work on other parts of myself before trying to coming up with those reasons. I am my own person and make my own decisions. If someone wants to criticize my decisions they'll get little reaction out of me. Luckily, in-laws/parents always love me so there's little chance of that ever happening

EDIT ~ I'm sorry if my original post seemed a bit condescending/spiteful, but threads like these remind me the miata.net forums... which were the location of many useless conversations. The miataturbo.net forums were so much more informational/practical in terms of the questions that were asked and the topics of discussion. I like to relate the two by saying miata.net was about how to drive your car like you rented it while miataturbo.net was about how to drive your car like you stole it. Only being on these forums for about a week I sense a bit of both mindsets, which is fine. There's nothing wrong with being in the middle. I just feel topics like gas mileage are better left for vehicles that were actually designed to give good gas mileage. When I'm driving a sports car the last thing I want to concern myself with is how boring can I make my drive so I can save a few bucks at the pump.

 

MTBE has been banned for over a year.

 

More tongue-in-cheek than hypothetical.
If I merely wanted to save a few bucks, I'd drive my Miata, but it is not a great highway car. AFAIC, long highway drives are pretty much going to be boring no matter what. I'll drive faster to get there faster or slower to see what kind of mileage I can get and to avoid speeding tickets, mostly depending on my mood I guess.

 

It took me a few tries to do the 55mph..... for a long time I would start out strong willed then the next thing I knew I was at the red-line again and again. The gas mileage of the rotary does not bother me at all now that I'm retired and driving very little. My 70' RX-2(my first of seven RX's) got 12mpg(driven hard) in town and 20mpg on the hwy and had 100hp. Now I get 16 in town and 23 hwy with twice the hp.

 

Only had my 8 few weeks I notice when the RPMs fall fewer than 4k the grin factor decreases significantly however, when I get the RPMs up the grin factor increases proportionally. So I’m shooting for a very good hgf (high grin factor).

 

It's really all about how you drive for the most part. In my 95 Miata I can get 35 mpg or I managed a low of 25 mpg with a 70% highway 30% city daily commute. Keeping it under the redline, accelerating slower and coasting down the hills does wonder in any car or truck. I did this very relaxed way of driving for about a week and figured with the gas prices at the time and my distance traveled a month I'd save about 33 bucks a month on gas by not punching the pedal down at every opportunity. To some people that might be worth it, especially if you drive a huge amount of miles a year. For me to be able to thrash my car around like I want to, it's well worth the ~$400 more a year in fuel costs.

However, it was actually fun to see how many mpg I could pull from the car without doing the extreme "hypermiling" techniques (basically tailgating large trucks on the freeway, shutting off the cars engine downhill / at stop lights and taking corners at dangerous speeds to avoid breaking). Keeping it at 60-65 on the highway, timing lights to get the greens and being a bit more conservative with driving style will keep you driving past those pumps : P Besides, it just means you can spend more time in the twisties tossing the car around like you should be : )

 

"shutting off the cars engine downhill " Our car does this automatically it turns off the fuel when coasting in gear. I see it on my Scan Gauge II it goes to 999mpg. Coast in neutral and your engine is using gas at idle.