15-16, Haven't seen mazda since 07 I prolly need an ecu flash. but if I don't hit 8k im not happy.

what?

I don't trust the dealership anymore. They tried to convince me I needed new brake pads after 11k, I checked them they had ALOT left, enough to get me too 42k. Tried to get me to buy new tires at 11k as well, they had plenty of tread left, not even close to the bars (if I remember correctly 8/32nds when i measured). Took it to them again at 15k and I of course needed tires again, came out with the all the tires worn on the tread bars (which doesnt make sense to me, unless the swaped them) I bought the tires and havent been back since ($1200). I wouldnt have bought them if it wasn't snowing and I had to be to workin in 2 hours. This doesn't include several other sketchy things. I just do all my own stuff now... Nothing really else left for me to do.

I have a little over 37,000 miles on mine and I'm not sure what's happened in the past couple of months. It's almost like my engine had a 32,000 mile break in period.

I used to be happy if I could get 17 mpg on an all highway, no A/C trip. I just went to Kentucky and back with the A/C on ALL the time and I did just over 22 mpg! What?

Also, based on a previous post in this thread, I've been trying to shift as close to 2,000 as possible. That's helped the local mileage tremendously.

Christopher

Just ran the numbers on my mileage since I bought the car at ~50k miles. Is it just me, or is the trend compellingly linear if we ignore the large spike caused by an entire tank of out-of-the-ordinary cruise control driving @70 (usual is mostly city)? I replaced my plugs just after the first data point, seems to have had no effect.

By my calculations using a linear fit, I should hit 0 MPG on Jan. 20, 2011 :crazy:
All's good, though. If I wait another year, I'll be GENERATING a gallon of gas every 10 miles! This renny is gonna make me rich :naughty:

Seriously, though, anyone have some insight as to what may be causing this? It seems (to me) that this downward trend in MPG over time is common in at least SOME '8s. I will be installing BHR ignition around Christmas, so we may be able to see something interesting. My coils are likely the originals. Gonna pull my plugs when I install the BHR kit to see if my old coils have messed 'em up.

Progman32, your car sounds like it needs some basic TLC maintenance. Coils, plugs, and airfilter will likely return the 16 city/20 highway numbers.

hey guys, i just bought my 05' rx8 (45k Miles) about 2 months ago. I have been getting 10-12 miles per gallon average from city driving. I usually cruise anywhere between 4000-7000 rpms because, to my understanding, its better for the engine. I'm unaware about the mazda flash update or what not and i'm wondering if it costs anything or if its a free update? Will it even help that much? I'm getting my car proffessionally tuned next week after I get my exhaust and CAI installed. will that make a difference either? Thanks in advance.

I have an '04 MT with close to 80K. I get ~17MPG city. Make sure your air filter is clean, oil checked ever ~500mi. Coils (known to go bad) will cause poor gas mileage as will dirty plugs. I recommend using premix (4-8 oz. 2 stroke oil) in the gas tank every fill-up.

I have not calculated my mileage yet, but mine is pretty bad.

Just changed the plugs and coils, wires will be here this week. Oil change and new filters.

So far I have gone about 70 miles on half tank. Yay. Looks like I need to start driving my Grand Cherokee again.

I've been calculating my MPG every time I fill up since I bought my car new in 04, currently about 92K miles on it.

My overall average is 19.17. See the chart for month to month and trending data.
(The dip in December 08 is not correct.)

The biggest tip I could give is to fill up your tank consistently meaning let the light come on and fill up until the pump shuts off. Filling up the same amount, or close to it, will result in better calculations of MPG.

for some reason i got 26mpg driving up to Plano this past weekend
that was my 1st long trip in my car

city mpg is around 16mpg

My 2004 6-spd is only averaging a very consistent 13.5 mpg for city/highway driving. As you can imagine, I am not thrilled about it.

Could new spark plugs, coils and wires plus a new air filter (old one is old but not too dirty) improve these numbers?

Thanks!

How many miles are on these maintenance items? I wouldn't let any of them go more than 30,000 miles, or less depending on your driving habits and conditions.

I just got the car with 73k miles, and I'm not sure if or when the plugs/coils etc have ever been changed. I believe the oil was changed regularly, the car is now driven conservatively. I'm hoping the coils/plugs/wires make an improvement. Any DIY threads here with pics? I have the technical manual.

Thank you!

Hey guys! I just got an Rx-8 a couple of days ago. I considered the mpg i was gonna get by getting this car, but now im considering just riding the bus to work b/c this car is gonna leave on the street if i keep going like this. well i read about the m flash for this car. So where do i get it? how do i know if the car has it already? bc i haven't calculated my mpg yet? but it's pretty bad!!!
It's an Blue '04, Grand Touring Automatic. 50000 miles on it.

I will sincerely apreciate Your help!!!

My 2004@80K still averages about 18mpg combined city/highway. I wish it was higher but the motorcycles offset it ; )

I am getting around 15mpg (take into account that I just bought the car two weeks ago and am driving it a bit more aggressively than I will on down the road) I read something earlier about the "M flash". Is that something a mazda dealer would do for the car? Anybody recommend doing this? Thanks

Just read lions post about 2 up lol... I'm in the same boat as you dude.

I've done it
 

I have discovered the secret to great gas mileage for our cars. No need to thank me. :ylsuper:

43k miles and getting 20mpg consistently while still getting on it at least 5 times per trip.. mostly city miles too.. weird huh?

Hey guys,

I changed the spark plugs, coils, wires and air filter. Oil has been maintained properly, the car is driven on shortish trips often up and down a mountain, and I'd say the mileage has improved from an average 12.9mpg to 13.6. Hot/cool engine cycle trip length is about 10 miles, which I know is not ideal for fuel efficiency of any car, especially that of a rotary that takes about 10 miles to get hot. The best ever mileage was done cruising in 6th over a long distance and retrieved 19mpg, but this was before the maintenance.

As you can probably tell, I'm not thrilled with an improvement of just .7mpg for my average driving needs. I've seen people mention an "ecu flash" but is that real or is it some voodoo that just echos in the forums and means nothing. If anyone has any ideas or recommendations, please, I'm all ears. Otherwise I may be selling the car.

Thanks!

More MPG via Springs
 

Different thought. I did all the maintenance and cleanup stuff in the First $100. I also did Plugs and Coils, got me from averaging around 19 to averaging around 20. Maybe 60% Highway, 40% City, flat roads, Florida. I made one recent change, and got an instant 10% increase (holding steady after 4 tanks). I swapped the stock springs for H-Tech (about an inch in the front, maybe .25 in the back). The lower front make the car look better, and the MPG went up instantly. I did the math today, springs will pay for themselves inside a year in gas savings. I have no idea if lower springs would have done more. That is for someone else to try.

Hi my name is Cole I have a 2005 rx-8 with 60,000 miles that is only getting about 8 mpg ecu has updated flash and have no code has any one had problem like this? Please help

Cole, I would recommend changing the air filter, the coils and the plugs. The stock coils last around 60K then they start weakening. Get your cat checked, if it is clogged it will kill your mpg. The cars on average get between 15~22 mpg, some better some worse. I get around 18mpg and I drive aggressively. At least once a day you should redline the car, these motors do not like carbon buildup.

Swiftnet thank you I did take it to the dealership and they said that they checked the coilsand that they where good. They told me a tune up would be good so changed the plugs out which it grab tpms a little quicker, and installed a knn air filter which the gas mpg got worst after I put that filter in? And everyonce in awile I get a really bad rotten egg smell in side the car?

Rotten egg smell is the cat. At 60K it should not stink. My cat died at around 65K, it fell apart and sounded like rocks in my exhaust.
You gotta be careful when choosing a Mazda Tech. I tried three different Mazda dealerships for maintenance until I got really frustrated at the poor outcomes. I contacted Mazda US HQ and they recommended I take the car to Tyrone Square Mazda, which was a 90 mile drive. That is the only dealership I will let touch my RX8. All the others were clueless. Whenever I need deeper maintenance on the 8, I take a 180 mile round trip drive. To give some perspective, I have three Mazda dealerships within 50 miles (15/20/45) and they all are technically challenged when it comes to the RX8.
Was your K&N filter a drop in replacement or does it bypass the OEM airbox?