Rotary Nut

In this thread I will report on my current and on going fuel consumption. I do this for those who wish to see real world figures as compared to what the mfgr has reported and for others on this forum to compare with their's.

The car is a daily driver and do not have much of a chance to "put it thru it's paces" as most of my driving is on a military installation during my morning commute. I generally do not flog it except when prompted or passing traffic on the interstate.

Check back from time to time as I will be updating the original post on a weekly basis or when ever I have to fill up.

Date.......Miles Driven......Fuel Used.....Oct.....MPG......City/HW
-----------------------------------------------------------------------
11/21/03........203.2............12.202.........87.....1 6.50.......80/20
11/26/03........248.2............12.994.........89.....1 9.10.......70/30
12/04/03........212.0............12.630.........89.....1 6.78.......100/0
12/09/03........221.8............12.509.........89.....1 7.73.......70/30
12/16/03........150.7..............9.351.........89..... 16.11.......100/0
12/19/03........242.9............13.106.........89.....1 8.53.......80/20
12/26/03........185.6............11.56...........89..... 16.05.......90/10
01/01/04........201.2............10.99...........89..... 18.30.......70/30
01/06/04........244.2............12.678.........89.....1 9.26.......30/70
01/14/04........175.5............11.57...........89..... 15.23.......90/10
01/21/04........192.2............12.005.........89.....1 6.01.......95/05
01/30/04........197.6............12.630.........89.....1 5.64.......95/05
02/19/04........189.0............11.726.........89.....1 6.11.......95/05
02/26/04........245.3............12.820.........89.....1 9.83.......70/30
03/01/04........253.0............12.608.........89.....2 0.07.......95/05
03/10/04........209.0............12.191.........89.....1 7.14.......100/0
03/19/04........180.3............10.941.........89.....1 6.48.......100/0
03/26/04........218.2............12.296.........89.....1 7.74.......90/10
04/02/04........225.7............12.246.........89.....1 8.43.......70/30
04/09/04........183.1............10.541.........89.....1 7.37.......70/30
04/20/04........215.2............12.553.........89.....1 6.99.......100/0
04/29/04........163.1..............9.163.........89..... 17.80.......100/0
05/04/04........263.8............12.448.........87.....21.19.......90/10
05/14/04........219.0............12.08...........87..... 18.12.......100/0
05/22/04........232.0............13.215.........87.....1 7.55.......80/20
05/28/04........152.0..............8.784.........87..... 17.30.......100/0
06/04/04........176.0............10.31...........87..... 17.07.......100/0
06/10/04........181.0..............9.43...........87.... .19.18.......70/30
06/18/04........119.0..............6.729.........87..... 17.68.......100/0
06/25/04........136.0..............7.464.........87..... 18.22.......100/0
06/30/04........153.0..............8.413.........87..... 18.18.......100/0
07/01/04........248.0..............9.54...........87.... .25.99.......0/100
07/02/04........232.0............11.210.........87.....2 0.69.......0/100
07/03/04..........53.0..............3.75...........87... ..14.13.......80/20
07/05/04........268.0............11.0580.......87.....24 .33.......0/100
07/08/04........276.0............12.275.........87.....2 2.48.......10/90
07/16/04........204.0............11.70...........87..... 17.43.......90/10
07/19/04........267.3............11.735.........87.....1 8.57.......10/90
07/23/04........196.0..............9.439.........87..... 20.76.......100/0
07/30/04........143.0..............8.376.........87..... 17.07.......100/0

Total miles on clock: 8857.00

Average miles per tank: 206.3461

Average days between tanks: 6.2

Max. miles per tank: 288.90

Fuel cost per mile: .0900

Current average is: 19.39 mpg

Bankotsu

nice..I been looking at the RX-8 for awhile now and planning to get one in the summer. Only thing that worried me the most was the mpg.

MP3Guy

You'll see the mileage consistently improve over time. Once there are some units with 10,000 miles plus, we'll see some people getting 25 highway- and then some.

Technique has a lot to do with it too. Although no one buys an 8 for mileage (I'm a bit puzzled by all the talk about it- this ain't no hybrid) squeezing the throttle on acceleration, and coasting when appropriate, will up the mileage considerably. My wife's Passat has one of those "instant readout" mileage displays which can be used to train your right foot. The turbo four gets 17.5 in stop and go traffic, and can achieve over 32 on pure highway, with level roads- with the wife and kids in it. Quite a spread.

I think we were all spoiled by the low gas prices we enjoyed- my Protege now takes $25 to fill up- quite a bit for an economy car!

Rotary Nut

Thats interesting!

I have owned three VW Passats ('95, '99, '02). The trick to squeezing the throttle is something the I trained myself to do just as you said. I liked that readout and think Mazda could do right by adding some sort of trip computer for things like this. Sadly I had my '02 Passat W8 repurchased under the VA lemon law. My RX for the most part is getting about the same mileage as the W8.

ptiemann

I disagree on the "continouesly improving mpg". Mine went up in the first 3 fillings = 700 miles, that's it. Then it staid continously around 20.

Here's the list of mpg values that I got from my RX-8. I'm at 4700 miles now. Looks very consistent. I do 90% highway driving.
The cheap no-name gas yielded 1 mpg less than 76.. big deal.
A couple of stop light races lowered it by 1 mpg. Who cares. Even stuck in traffic for an hour, I got > 20.

Then only thing that I notice now is that warming up the car in idle made a difference on two cycles.


mpg ….. Gas Brand ….. Octane
17.26 ….. Gas from Dealer ….. 87 Oct
18.18 ….. Texaco ….. 91 Oct
18.67 ….. 76, Capitola ….. 91 Oct
19.47 ….. 76, Watsonville ….. 91 Oct aggressive driving
20.45 ….. 76, Capitola ….. 87 Oct speeding 80 - 110mph
21.21 ….. Texaco, Traci ….. 87 Oct
18.94 ….. 76, Menlo Park ….. 87 Oct some red light racing, idling to warm up
21.18 ….. 76, Capitola ….. 87 Oct 70-80 mph, no "warming up"
20.96 ….. 76, Menlo Park ….. 87 Oct 1 hour stop and go
20.47 ….. 76, Capitola ….. 91 Oct
20.38 ….. 76, Capitola ….. 91 Oct 30 minutes stop and go, speeding
20.25 ….. 76, Capitola ….. 87 Oct
19.63 ….. AJ's, Soquel ….. 87 Oct
19.69 ….. 76, Capitola ….. 87 Oct
20.00 ….. Chevron, S.Cruz ….. 87 Oct
19.30 ….. 76, Capitola ….. 91 Oct
20.88 ….. BP, Menlo Park ….. 87 Oct
19.37 ….. Willow, Menlo Park ….. 87 Oct


hope the table is readable once it's posted.

ptiemann

thanks MP3guy, I'll definitely try out the squeezing part. Other than that, I'm ok with my car's mileage.

-Peter

RX-GR8

what do you mean by squeezing the throttle?

ptiemann

I thought it means 'floor it' . If that helps, I'll floor it as often as I can! For one tank.

Dave Gotwisner

I've been reading these threads on the MPG issues, so I decided to try a test.

As a point of comparison, my old RX8 (since returned to get the dealer markup back), I was consistently getting 18-19 MPG, and had about 5K miles on it when I returned it.

With the new car, I have about 2K miles, and consistently shift around 3K RPM (except for first->second where I sometimes shift higher). Again, on this car, I was consistently getting 18-20.

For the last tank, I decided to drive it a little differently (changing shift points). I started shifting first->second between 5K and 6K almost always (a few times I shifted at 7K). For other gears, I started shifting between 4-5K. When possible I will drive fast in 6th (last tank I drove over 100 several times, maxed at about 110; this tank, I took it above 120 once or twice).

Driving is mostly highway with some city (probably 70/30, although highway ranges from commute to no traffic).

For gas, I always use Chevron 91 octane.

The tank that I just completed got a little over 18. I don't see how anyone can realistically drive the car and get 13, unless there is some problem with the car (not with the driving style).

ptiemann

I fully agree with Dave Gotwisner. Those people getting 13 mpg, and at least one of them even when driving old-lady style..

they should raise hell at their dealership.

Thanks to this site they can make case.

MazdaManiac

iTrader: (3)

And I will do just that when I bring it in for the first oil change.

I am on tank number 7 with 1430 or so miles on the odometer.
My mileage has been getting progressively worse with each fill-up.
My first 4 tanks yeided about 16 - 17 MPG and I lost 1 MPG per tank after that. I'm down in the 13 MPG range now.
Each tank had a distinctively different type of driving consume the majority of the gas - all highway on one, all city on the next, stop and go bumper-to-bumper traffic for another.
I didn't buy the car for its gas mileage, but my turbo 2.5 liter MX-3 got 18 MPG if I raced the entire tank. I got closer to 26 on the highway. My Miata gets the same as the MX-3 did and it has bigger injectors.
At this rate I will be getting 0 MPG by the time I hit 3000 miles on the odometer.

rxtreme

iTrader: (1)

I think I've been driving on the same post Rotary Nut has been driving on and have been consistently getting 16-18 MPG. The majority of my driving has been short trips city driving (on post most of the time). Alot of the short trips have been from cold starts so I'm not surprised I don't break 20 MPG. Oh, and I like to lay on the gas after it's warmed up so I'm not surprised my mileage isn't better. Oh, well.

Rotary Nut

Yep that was me!

MP3Guy

No!! It means the opposite! Although flooring it is more fun. Seriously, if you're just out trundling to grandma's (like tomorrow for instance) with the family, a bit of judicious throttle use will do wonders.

There is a strange sense of accomplishment to squeezing all you can out of a gallon of gas, much as there is carving up your favorite right hand decreasing radius sweeper.

But that's just me! :D

Rotary Nut

Upon taking deliver of my RX the car did not have the window sticker affixed to the window as per federal law. I just recieved a brand new sticker from Mazda.

The sticker shows 18 mpg city and 25 mpg highway.

In smaller print at the bottom where it shows the EPA ratings it shows avererages of both high and low side of your expected fuel economy.

It states tha results reported to the EPA indicate that the majority of vehicles with these estimates will achieve between:

City will average between 15 and 21 mpg

Highway will average between 21 and 29 mpg.

With an estimated annual fuel cost of $1142.

ndsind1

Why would you ever put 83 octane gas in your rx8? is that a typo? I can understand 87 octane but it even says in the manual that anything under 87 octane can cause damage to your car.

Rotary Nut

Well I said it was an experiment!. I put in regular since some members were experiencing better fuel economy. I then experienced pinging at 6000 rpm and stopped using 83 oct, and moved up to mid-grade.

ptiemann

I take it you're from Virginia, USA? (I'm asking because overseas, they have a different sort of octane rating, with "our" 87 is called 91 there or so.. )

In California, they don't offer anything below 87. It's actually the first time I ever heard of an 83 gas. Was that offered at a regular gas station??? Is that common in Virginia? What kind of car uses that gas? Must have to do with the California emission standards.

pp13bnos

I only wish I could get 20mpg. I've been granny driving my car and I'm only getting around 14mpg. My granny driving is 4k in first, and 3k in every other gear. My driving consists of a 7 mile one way commute. All country roads with 4 stops. Max speed is around 60mph. I'm realy hoping that with more miles (I have around 800 at the moment) the fuel economy will come up.

CJ

Haze

Man -

I'm afraid that your car is not going to get very much better mileage like that. Driving only 7 miles on a one way commute, I assume to work, your car is spending almost the entire trip on choke. Until the engine heats up, it's using considerably more gas than when hot. All the best and sorry.

budwei

In VA we have 83 - 87 - 93 . I use 83 on the van and 93 on Miata and RSX

MazdaManiac

iTrader: (3)

Interesting.
Most of the gas stations around here in suburban Maryland have some combination of 87, 89, 91 and 93.
I've never seen 83 and I stopped seeing 85 a few years back.
Sunoco even has 94 and in some spots I've even seen 95.
In New Jersey, I stopped in a Sunoco a few years back and they had the "Red Label" 98 octane stuff.
I guess they have a lot of old-school hot-rodders living around there.
I use 93. It isn't worth the $1 per fill-up difference to use 91.
However, I do acknowledge that 91 has a higher energy potential.
You always want to run the lowest octane you can for maximum power.
I just don't trust the uniformity of the local gas "entrepreneurs" and the mish-mosh of oxygenated fuel and whatever crap they blend in. Who really can tell what the true anti-knock index is of the local fuel.
Better save than sorry.

Isamu

I've got like 3500 miles on mine and am still getting 13-19 mpg, 13 being pure city and 19 being pure highway. I think it's the way I'm shifting, or as some of you mentioned... not warmed up enough? So what IS the proper way to do this? My commute is short, like 5 miles one way max. I shift around 4k usually to hopefully bring up the mpg. Not working... should I warm the car in idle before starting up the short commute?

ptiemann

shifting at 4k is the way to go to conserve gas, I just think that your trips are too short. It's warming up half the time and if I understood it right, it's running a richer air/fuel mixture there. There's a thread in the tech garage about the A/F ratio, check it out.

So, yes, you get inferior miles per gallon than me, but you still use a lot less gas than me. I'm driving 48 miles one way and wouldn't mind a 7 miles commute.

selmeralto

I'm very interested in ptiemann's post. I have the same driving pattern as Isamu (4 mile city commute from a cold start) and the same gas mileage (around 13). Ptiemann suggested tracking down the A/F thread which I did do. I found it inconclusive.

Can Ptiemann or someone else confirm that the choke is on in such a situation and that, as a result , the mileage would suffer that much?

Many thanks.