NEW CAR Gas Mileage Shock!!
 

Let me begin by saying that I just picked up my Winning Blue RX-8 Today!! Loved every second being inside or next to the car so far. This forum has helped me make the decision on the RX-8 (Rather than G35) in numerous ways. Thank you all. I've already anticipated lower than par gas mileage on my 8, paper reads 18/24, and from reading you guys' feedbacks I would estimate around at 17-19 mpg if I do all high way driving. But to my shock, when I got home from the dealer, which was exactly 93 miles away (odometer reading), I was at the border of 1/2 tank already! Is there something wrong with my RX-8? Is it always this low? I mean....full tank is close to 16 gallons right? I wouldnt even hit 13 mpg! And My travel back home was all highway also. If anyone knows of anything about this or any advice, please help me out. :(

New engine needs to break-in. Gas Mileage will slowly improve

dude break in always takes alot of gas..!

expect to get about 240-270 depending on your driving style on a full tank. I've pushed it to 175 before it reached gas light... and that was driving as fast as I can on surface street.

wow outlaw your sig is awesome!

Try not using your gas guage times tank capacity as a mpg meter. It doesn't work very well. Use paper and pencil and gas slips.

I agree. There's no way you can calculate mpg by looking at your gas gauge. It's likely that the tank was really full when you picked it up. Try filling the tank and setting your trip odometer. Then drive until it's at least below the 1/4 tank mark, fill it again and divide the mileage on the trip odometer by the number of gallons needed to fill it up.

The most gas i have ever pumped was 13.8 gallons into my tank. I run it until the light comes on and the needle is on E. That shows that there is obviously a difference between the gas gauge and the size of the tank( 16 gal i think). I just keep track of my mileage and how much it takes to fill up the tank (until the pump clicks off when filling). That will give you more accurate results than using the total size of the tank.

The tank is nearly 16gal, but only about 15 gal is useable and that's pushing it. 2nd - if you just picked up the car, it probably wasn't "full" to begin with. FWIW, my first tank was 285 miles, 20.8 mpg. I know they filled it up about 1 mile from the dealership (part of why it had 8 miles when I got it) when I picked it up.
At the 1/2 mark on your gauge you have used about 6.8 gallons from a 'full' tank. If you do read a lot about mileage on this forum you will find that more than just a small percentage of owners are getting in the 14-18 MPG range. I very glad I'm not one of them. I have a hard time comprehending how such a variance can exist, but apparently it has much to do with the engines being made by hand. Good luck w/ yours!

welcome to the mix...

Re: NEW CAR Gas Mileage Shock!!
 

No problems... I had the same "gas gauge shock" on my first tank. Then I realized that the gauge was just a lot different than my other cars have been - they have fallen very slowly on the top 1/2 and then it speeded way up - the gauge on my 8 seems to plummet and then take disprportionately long to get from just over 1/2 to jut under - and then it speeds up again. If yours is behaving like mine, you'll need about 13 gallons at around 225-250 miles. I've never gone more than 250 miles on a tank, but I've never put in more than 14 gallons - when the needle was reading negative empty.

Wow, thanks for all the input guys. I guess i'll need to wait and see how things go after the break in period. I certainly hope my 8 isn't in that small % that gets 14-18 mpg. How can there be such a big discrepency in gas mileage among the RX-8s' anyways? Did I get a lemon? Has anyone complained or heard from Mazda regarding the their actual mpg and the factory sticker of 18/24?

Don't you think you're getting a little ahead of yourself? You just picked the car up this morning and you're already wondering if it isn't a lemon because the gas gauge went down a little faster than you expected. Drive and enjoy the car for a while before you start worrying about small details like this. If you do a search about MPG, you'll see a number of threads that talk about this in great detail. Most say that the gas mileage improves as the car is broken in. Mine has varied from around 17-21 MPG depending on when I checked and the type of driving I had been doing. I don't even bother to check but about every 2 months.

Yeah, my car is one of those small percentage cars, my first 5 tanks or so was arond 13-15MPG, a whole bunch in the middle of the pack between 13 and 22, last 2 have been 18-20... slow break in, not driving as hard, latest pcm flash??? who knows.

Go on a road trip once it's broken in, you should get descent mileage then, my best was 22+MPG 100% highway, but that was in January.

I know exactly how you feel. I picked up my car last week with 44 miles on it. The first day I drove it to work, I could actually see the needle dropping. :o I only got 200 miles on that 1st tank. I was feeling quite ill about it considering I drive about 75 miles a day, and gas prices heading towards $2.50/gal. I did take a few things into consideration -
* The tank was probably not completely filled in the first place.
* During test drives (including my own) the car was driven pretty hard - accounting for some poor gas mileage there.
* The car was driven to my dealership from another (about 35 miles), and chances are they had a little fun with it.
* I've been told by several people that gas mileage will improve after the break-in period.

After filling up, I got over 18 mpg on my first full tank of gas. I'm still working on the 2nd now.

Also, as affenage mentioned - the gas gauge does not drop the way most have on my previous cars. The quick drop seems to be in the first half, and then it greatly slows below 1/2. During that first tank, I thought I was only getting around 10mpg! Not a good feeling. But all seems much better now, and the car is awesome! Enjoy. :D

I am averaging about 17mpg on my RX-8 so far. Mine is the auto, is there any difference in the stick?

Same thing happened to me when purchased.

Now with 2400 miles and the M flash, it has improved A LOT!!

Everett

Thanks for the support guys. Believe me, I have NO INTENSIONS to give up the 8!! It's the funniest car i've ever driven. But just like Green thunder, I I have to drive about 85 miles to and from work daily. I'll just chill out for now, enjoy everything about the car, and See how things go! Thanks again. Oh yeah BTW, what is this M Flash, L flash, PCM flash thing I read about in the other sections of the forum? Please let me know if it's something I';ll need to do later.

I've gone through three tanks so far. The first tank was barely 18 mpg, the second was 20.5, and the last was 19. There doesn't seem to be any rhyme or reason for the different rates, I've been driving basically the same. Maybe I got on the car toward the end of the last tank.

I've been driving mostly highway (90%), switching gears at about 3500-4000 rpms. Does anyone know if I should be changing gears sooner or later than that?

Your mileage will improve. Make sure you have the M flash. They will not flash it as a car on the lot. You will have to ask for it. Search for M flash for details.I just finished my second tank 19.99 mpg in mixed driving after the M flash. Before the flash I got 16.5 to 16.9 now I get 19.2 to 19.99. I didn't get it for the mileage but I am very satisfied with the way it runs now and with the mileage. I bet I can get 26 mpg on a trip (i got 24.2 before).

I've yet to figure out the anomaly with my MPG. I'm on my third tank. The first one, right from the dealer, I did 313 miles and got 24 MPG. I was driving it fairly conservative, but not overly so. The second tank, with a little more aggressive driving, I got 240 miles and a little over 18 MPG. The third tank I got 260 miles and just under 20 MPG.

I have no idea what gas the dealer put in, but I'd love to know. That'll probably be the best I ever do. As long as I'm in the 18 MPG range in my mostly highway driving, I'll be satisfied.

Re: NEW CAR Gas Mileage Shock!!
 

Just a tiny correction: gas tank is 14.9 gallons.

ZGlide,

After reading your question about the M Flash, I did some searching and came across this thread:

https://www.rx8club.com/showthread.p...threadid=25613

Phew! I read all 20 pages in that thread. Looks like I will most likely need the re-flashing even though I just got my car last week. It was built in 02/04 and its serial number is lower than the one on the TSB. I'll try the brake test, but will probably ask them to do it when I take it in for its next service.

My mpg improved 4mpg after 10k miles on car....you will too... be tender at first and you will love it even more after it frees up!

I actually ran out of gas last week.
My light came on at 200 miles like it always does and 27 miles later I was all out and it stopped running.
It was a little over a 15 mile walk to the nearest open gas station (I could have called someone or AAA, but it was the first really beautiful night here and I was wearing running shoes).
I brought back one gallon and filled it and drove the 15+ miles to the station where it ran out again as I was pulling into the pumps!
That is 15.2 MPG. Confirmed, obviously.

My gauge is the most linear gas gauge I have ever seen.
50 miles to 3/4, 100 to 1/2, 150 to 1/4 and 200 to E and the light.
1.8 gallons or 27 miles on the light 'till empty.

The precision of it almost makes me forget how crappy my mileage actually is.