Rotary Nut

WTF!

I know this has been beaten to death but I just needed to share this you guys and gals and also get your opinions on what I just observed.

I was finaly able to get my 8 out on an "extended" road trip this past weekend. I drove to the Short pump mall in Richmond VA from my home in Newport news.

Now normaly one would think that the more highway miles driven on a tank the better the mpg or for that matter being able to get more miles driven on that tank. But nooooooo, not with this car!

On my last tank (19 Feb) I drove mostly city driving with one 70 mile round trip to VA beach. I drove 245.3 miles on that tank over a period of eight days. Now the last tank I got the following:

Miles driven: 245.3, Fuel used: 12.820, MPG: 19.83

Now this past fill up (on 27 Feb) The total miles driven includes the trip to Richmond (and then some) which was 198 miles round trip, straight highway driving while using the cruise control, driving at 70-75 mph for most of the trip. In three days of driving I got the following:

Miles driven: 253.0, Fuel used: 12.608, MPG: 20.079

Technicaly I was only able to get the same miles (253 vs. 245.3) per tank between the two fillups. The low fuel light came on just before filling up on both tanks. The mpg was for the most part the same whether I drove 70 miles or 198 miles highway between tanks. I only saw a .249 mpg increase for 128 miles more miles driven at highway speeds.

You would think I would have gotten better mpg or at least more miles on the tank while driving more highway miles. This is totaly whacked!

P.S. I actually heard the RPM warning buzzer during a spirited jaunt on I95! Whoo hoo!

zoom44

you're into the rich 2nd intake open maps when at 75. try cruise at 65 next time . you should be able to get 24 or better there depending on conditions. btw same gas and octane between those 2 tanks?

D MENAC 7

OK, I just went on a road trip and cruised at around 75-77 and was able to pull off a tank full at 300.5 miles. It took 14.11 US gallons. That's 21.3 mpg, a record for my 8 and I was traveling into a slight head wind. I was close to running out of gas by my caculations and stopped at the first station as soon as pulling into town.

My mileage on the whole trip never went below 20 and I did it all at 75-77 mph. I will never complain about the gas mileage again, it only sucks in town even if I granny drive which I ain't no granny.

RX-GR8

i have no complaints on the highway. i get 20-21 highway at 65-75 MPH but 100% city is bad. 12-13 MPG but my commute is 5 miles each way. by the time its warmed up i'm at work and shutting it down. i'm taking it in on the 12th for the 2 recalls, brake squeal, clutch noise(when not engaged) and i'll ask about the ECU flash then.

Rotary Nut

Zoom 44 - yes the same station, same 89 octane

D MENAC 7 - My low fuel light comes on at the same point and always takes the same amount of fuel (12.5 gals) so how can you get 14.11 on the tank. Didn't you not get the low fuel light?

D MENAC 7

Oh, I got the low fuel light and I was 35 miles out of town. Don't think that last 10 I wasn't making plans on who was the closest who could come and bail my *** out. LOL I was starting to sweat it and did slow down to 65 and drafted a huge RV for that last few miles.

D MENAC 7

Oh yeah, 87 octane all the way there and back.

D MENAC 7

In town, just like RX-GR8, I get 13-14 mph and I also have a short commute with about 6-7 miles one way but a lot of lights and stopping and going.

RX-GR8

all my 8 has ever seen is 93 octane. menac have you ever tried 89 or above? why 87?

zoom44

hell i put 1/2 gallon less than capacity in after doing 310-315 in mine with the light on for the last 9 miles. most of the last 25 were on regular roads not higways. it was super scary at night in unfamiliar area in northern cali with my wife glaring at me from the passenger seat. wont push it like that again- wife would hurt me really bad.

D MENAC 7

Yes, I have tried 89, 90 and 92 and none have proven any more or less for the way it runs or the gas mileage.

Why 87? I have read the thread on here about 87 and it seems to do just fine. Why pay more for nothing in mileage or performance. I have recorded all my tankfulls and driving habits and cannot see any varience.

D MENAC 7

Yeah, my wife was there and I assured her we would make it. I had her believing me more than I believed myself, didn't sweat it, I am a good poker player.

zoom44

i was sweating buckets and she could tell even in the dark. i kept saying "we'll make it dont worry" but i really had my doubts.

khoney

I've driven 12000 miles so far. Every single tank except maybe the first 2 or 3 has been between 18 and 21MPG, with the vast majority being about 19.5. Many different types of city/hwy driving, and I take it to 9K whenever I can.

RX-GR8

yea i read that thread too. just was wondering if there was a performance loss and a MPG gain from using it.

Mitch Strickler

I don't understand the panic about the low fuel light. Sure, I fill up soon after I see it -- why not get it over with? -- but I'm not afraid I'll run out of gas.

Instrument readings and mileage claims may not be reliable, but when a car manufacturer says its tank holds 15.9 gallons, it holds 15.9 gallons. That doesn't vary in production; it doesn't shrink with age. 15.9.

Once you have seen the light on your car a few times, and noted how much less a full fillup is than 15.9, and made sure it is about the same amount under 15.9 each time (in other words, that your light comes on at the same point each time), you can be damned sure how much gas is left.

The miles left calculation is pretty exact, too. Based on mileage before the light comes on and the kind of driving you have been doing, you can tell if the car is giving the same mileage it has in the past. Then you just apply that past mileage to the kind of driving you will be doing with the light on, and you know how many miles you can drive before it really goes dry.

Think, then relax.

D MENAC 7

Ahhh, I couldn't remember how large the tank was, I thought it was in the 14.5 gallons, not 15.9. Hell, I didn't have to sweat at all then. I didn't have my manual so I just didn't really know. That needle was past empty and I haven't had my car long enough to know it that well. So, from now on, I have a better understanding.

My wife does bitch at me once in a while that I shouldn't let the tank get so low that it isn't good for the car. I always wondered about that because I hardly ever fill up before it's almost to the E.

She claims her mechanic Father always said that it wasn't good and I always argued that with todays's car's fuel injection and computer management it didn't matter. What does anyone think about that??

MaRX8

I've been told that the RX-8 begins to run very lean at 4200 RPM, after your break the 4200 RPM barrier it starts to inject more fuel. Keep it under 4200 RPM and you should get better fuel econ.

swoope

iTrader: (5)

[QUOTE]Originally posted by Rotary Nut
[B]WTF!

I know this has been beaten to death but I just needed to share this you guys and gals and also get your opinions on what I just observed.

I was finaly able to get my 8 out on an "extended" road trip this past weekend. I drove to the Short pump mall in Richmond VA from my home in Newport news.

--------------------------------

short pump mall????

god how it must have changed, short pump was just a place you might get gas on the way back from wintergreen. a mall, thats wack.

as to the milage issue. for me worst 18mpg best 23mpg. most lite city with ac.

i think if you go above 75mph. it goes down.

beers

Nubo

probably lost a gallon right there! :D

RX8by

I just got 25.0 mpg on a trip to Dubuque, IA. It was mostly 2 lane roads. I cruised at 60-65. It you go over 70 you RPM goes to high and you really burn the fuel.

DemonRX-8

Hell, I wouldn't complain if I say anything near 19-20 mpg. I've observed 14.5-15 mpg since I bought the car, with one tank dipping down to 13. The last tank consisted mostly of hwy miles driving a 35 mile stretch each way for the most part and still barely cracked 15! Gotta look into getting that ECU reflash.

D MENAC 7

I have not noticed any appreciable performance loss by using 87 octane. I have considered putting an octane booster in just to see what that would do but just have never taken the oportunity to do anything abouut that. If I do, I would want to do it with a bit of semi-accurate testing, not that I can do it to the nth degree because I do not have any real test equipment. It would have to be done with the seat of my pants observation.

Sue Esponte

Does the RX8 have a trip computer that measures average MPG?

-Eric

Positron

Nope. Trip computers A and B only measure miles traveled since reset. Mazda didn't include the Average or Instantaneous MPG or speed functions. Too bad.

m