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Mazda RX-8 Gas Mileage Reports



  • I took my 2005 AT in last month for the voluntary recall, and among other things they "upgraded" my PCM. Since then I've noticed about a 1 MPG decline in fuel efficiency. My MPG average for the month before the upgrade was 18.6. Since then it has been 17.6, with no change in driving patterns. Some upgrade!
  • pathstar1pathstar1 Posts: 1,015
    The upgrade could have addressed other issues such as engine life. At any rate, with winter here 1 MPG loss is pretty good. It alone often causes 3-5 MPG loss.

    If you think "upgrades" should address fuel efficiency, time to buy a Prius. ;)
  • Winter? What's that? I live in Malibu!
    Seriously, the cause and effect is quite clear in my case. The lower MPG started immediately with the next tank after the upgrade, and the highest MPG since then hasn't matched the lowest MPG for the month before that.
    I didn't expect an upgrade to "address" MPG. I knew what I was buying, and it is worth it. I just didn't expect it to degrade MPG.
  • trispectrispec Posts: 305
    Good one. Winter in Malibu LOL. I think pathstar is from Canada though LOL.

    OTOH, my 2005 RX-8 AT seems to be getting slightly better MPG since the lastest PCM flash. Just got back from my annual 2000 mile trip from Boston to the mountains of NC. On one stretch I got 25.2 MPG with lots of 70-90MPH non-cruise driving on new years day.
  • Well, I'm glad at least someone is getting good mileage! :)
  • trispectrispec Posts: 305
    Also, just to add, we've just starting getting some colder temps here in Boston, 9 to 15 degrees in the mornings. Last year, I remember getting horrible 12MPG city driving only, but with my last fill up MPG showed 15MPG city driving only. Now I am driving my RX-8 AT kind of easy these days in full auto mode only, but I'm still thinking 10-20% better MPG since the last PCM.
  • mba2dnamba2dna Posts: 8
    Now, my 8 has 15000 miles, it is around 18 mpg for city and 23 mpg for highway. ;)
  • dprfddprfd Posts: 1
    Own 2005 Mazda RX8. Emission Recall 4206F installed and immediately realized 3 MPG loss in gas mileage. After returning car to dealer and several "inspections" later Mazda dealer basically says "tough". Too bad for gas mileage but you should realize better power performance. Mazda did not inform me before (or after) that gas mileage would be affected by this recall. The recall tested for issues I did not have. The result was me paying 8 - 10 dollars more every time I filled up. Please all Mazda RX8 owners need to band together and make Mazda do something.
    If I took $30 from your wallet every month, I would be put in jail. Called stealing... Can you say "Class Action Law Suite". If you are thinking about buying a Mazda RX8... DON'T!
  • dwynnedwynne Posts: 4,018
    Didn't you research the MPG on the 8 before you purchased? I did, and I knew from the EPA numbers and from lots of other current owners that the mileage would hurl. And it does. I get 14-16mpg on my commute VS 23-24mpg in the S2000 and 27mpg in the xB. It get under 20mpg on a long trip (fill up, drive 70 mph, fill up).

    Yes, I don't like it, but yes I was expecting it. My car is also an 05 with 6mt and probably had updated firmware when I picked it up - I had asked the dealer to be sure that was up to date, pre-delivery. The cat converter recall had no affect positive or negative with the mileage.

    Folks here and on the various 8 message boards report better mileage than I get. If they also have 6mt cars, then I assume the are just putting around in them. I drive mine as it was designed - like a sports car - and I am sure the mileage suffers. If I want to putt around, I can take the xB and drive it hard and still get 27mph, or the S2000 can be driven to the redline and do no worse the 23mph. I got a sports car that got bad mileage, but knew that going in. So while I complain about it, it IS my fault :D

  • trispectrispec Posts: 305
    I've got the 2005 RX-8 AT. After the last PCM flash I actually think I'm getting 10% better gas millage, but then again, I think mt RX-8 has always gotten great millage. For example, on all of my long driving trips (2000 miles), I average 80MPH and get 23MPG. On shorter trips where I average 50-60MPH, millage is 25MPG.

    Sure city is still 15-16PMG, but here in Boston, pay back comes from roads that are such an incredible snaking jumble of cow paths. If you can stay out of traffic jams, driving in Boston is a nice balancing of G forces in all directions.
  • trispectrispec Posts: 305
    Just take a look at the new real world federal millage rating system. The most interesting thing is how close the RX-8 comes to competitors. S2000, Z350, G35, and 'Stang are all only one or two MPG better in the city.
  • dwynnedwynne Posts: 4,018
    I own both an 05 S2000 and an 05 RX-8 (6 speed).

    I just came back from a trip to the mountains in the S, over 30mpg on the highway (all top down) and 26-29 mpg driving around the mountains (all top down). I get 24 mpg commuting to work (mostly all top down).

    My RX-8 with the latest recalls and computer flash gets 14-15 mpg commuting (same route as the S gets 24 mpg) and gets 19 mpg on highway trips - though one time I got 20.5 mpg. And highway driving is mostly set the cruise on 74 or 75 and just ride - so not much room to improve the mileage except to drive slower.

    So it does not matter if you use the old or new EPA numbers, when driven as intended the 8 suck fuel like a huge v-8 (or worse). So says all the car mag tests and so say the customers who drive (the 6 speed) in a spirited manner.

    In a recent C&R head to head with the 2007 Ford Mustang Shelby GT, the 2007 Mazda RX-8, the 2007 Nissan 350Z, and the 2008 Audi TT 2.0T guess which car "won" the test? Even though it "guzzles gas like a private jet" ?

    link to story

    Note on their 600 mile test the 8 returned the worst mileage at 15mpg - even lower than the 319 hp Shelby.

    I love the car, like C&D I think it is a "winner", but when driven as designed the MPG just sucks :cry:

  • trispectrispec Posts: 305
    Well MPG isn't much of point to push with the RX-8, but my paddle shifter RX-8 AT seems to get better than your 6 speed RX-8 MT. For example, I average 80MPH on my Boston to Portland evening run and fill up to fill up I get 23MPG. I have gotten 25MPG on a steady 60MPG runs to the Cape. My work commute these days is running 18MPG.

    I don't do much paddle shifting any more though, so that may help keep the RPM's down well below 2000 most of the time. I do regularly rev past 5000 and oil consumption in the city is a quart/1000miles.

    Thanks for that link. I sure love my RX-8. It still turns heads, especially when four 6' adults exit with all the door open.
  • dat2dat2 Posts: 251
    Yeah I agree the RX8 is an amazing ride, just too bad the mpg and lack of torque (no faster than a Nissan Sentra Se-R). I drive a 350Z and normally get 28 mpg at hiway speeds (70-85mph) and about 21 in city driving. And the EPA for my 350Z was 19/25, so obviously they under rated the mpg! And it seems the mpg is overly generous for the RX!
  • tomnavytomnavy Posts: 2
    Two points you make; first, mpg. In commuting to work I normally get 19mpg--not great but not that bad.This includes stop and go driving using the freeway.Total freeway, the mpg increases to 21-22. My brother-in-law's infinity G-35 coupe gets about the same.Both cars are 2004 models. Very little difference here. As for lack of torque, the G-35 has about 100lb-ft more torque--yet he can't beat me in a race to 100mph.If torque is so important then why can't he beat me? The answer lies in the relationship between hp and torque. It is difficult to measure hp directly in a rotating device such as a engine,but measuring torque is straight forward.From this torque, one can convert it to hp.There is a math formula for this--but it is rpm dependent.Thus a car such as the rx8 that has low torque can have alot of horse power if it can have high engine revolutions.Thus at 8500rpm it generates about 240hp.So the reason I can beat my bother-in-law's G-35 is that I drive my rx8 at its hp max--that is 8500rpm.At this power max my hp to weight ratio is about the same as that of the G-35. So the bottom line is torque and rpm tells you how you must drive your car to get max power.
  • sssfegysssfegy Posts: 132
    dat2, the 350Z is a very nice car for people who like muscle car looks and ride, I could not sit in the 350Z on the race track for more than 20 minutes and my back was killing me, so I am not sure how long of a commute you can sit in the car without taking a brake. Now the 8, as comfortable as a Porsche, you can drive it for the full price you pay.
  • trispectrispec Posts: 305
    Agreed, the Z is a track and highway racer. The RX-8 is usable even on really bad roads.
  • mdw1000mdw1000 Posts: 171
    The Z has more power, the 8 has a better ride and a back seat. I haven't driven a Z, but I'm guessing the 8 feels much more agile due to a lower "polar moment of yaw" as one of the brochures puts it. Basically the engine is further away from the front end of the car, so it is easier to rotate.

    The fuel economy/power output ratio of the 8 isn't that great, but the rotary engine has other benefits - smaller, lighter weight, etc. Plus you can rev it a lot without worrying about reducing its life, unlike a piston engine. Rotaries are designed to rev, in fact it is good for them.
  • trispectrispec Posts: 305
    My MPG has improved 20% since I bought my RX-8 AT new. After 30K I now get 17MPG in the city where a year ago I was getting 14MPG in the city. The first few months of ownership I was only getting 13MPG.

    As for revving, there seems to be a quicker and smoother rise right up to the 7500 red line beep. It took at least a year before the full auto mode would reach red line to set off the beeper. It was a huge surprise the day it happened.

    As for the 350Z's ride, I use to drive a consultant back to his hotel from work here in Boston. He owned a fully tricked out 350Z back in Arizona where he lived. Of my RX-8 AT he was very impressed with the rides ability to handle Boston's horrible streets. He concluded one would never be able to drive a 350Z in Boston without getting a severe back ache. He also said that he'd taken his 350Z on the track and averaged only 6MPG.
  • mdw1000mdw1000 Posts: 171
    Interesting. I know there is a saying that "a rotary's fastest lap is it's last lap." Apparently they have a reputation for getting better as they age.
  • avelectroavelectro Posts: 9
    My 2007 AT RX-8's best mileage was its latest fillup, 303 miles took 11.2 gallons = 27 mpg. :) This was from a daily commute of 30% suburban 10% urban and 60% traffic-jammed highway. The car just turned 7000 miles and has been averaging 25 mpg on this same commute, but I recently changed the engine oil from 15W-50 to 5W-40 which feels noticeably better (peppier).
    I keep the tires at 40 psi but that doesn't explain why my mpg numbers are so much higher than the EPA numbers. I do avoid tailgating so in bumper-to-bumper highway traffic I am leaving a deacceleration cushion space ahead of my car whereas most drivers seem to be constantly riding their brakes. I am sure this practice helps alot since I am using the paddle shifters to slow down and I think the fuel computer shuts off the fuel injection during engine braking. Also, the AT drops into 6th between 40 & 45 mph and is geared so 60 mph is right at 2000 rpm.
    I also use 1oz of Marvel Mystery Oil per gallon of fuel to help keep the engine innards clean but I doubt on such a new engine this will affect efficiency enough to notice.

    So I am very happy with my RX-8's fuel economy numbers. I just wish Mazda could get those EPA numbers closer to my reality.
  • The new Federal standards match my normal MPG 15 City, 23 High Way. But if I drive to the Cape at 60mph cruise control, I get the 27MPG you get.

    My RX-8 AT is mostly driven in city in manual mode in 2nd gear. 3rd and 4th would be dropping RPM's in down to 1200 where carbon build up is noticeable. I keep the RPM 2500-3500 in 2nd which covers all the city speeds up to 45MPH.

    I saw a piece about an engine additive that kept rotor housing shiny sparkling inside.
  • avelectro wrote, "... is geared so 60 mph is right at 2000 rpm."

    I wish the 6 speed manual's top gear was also such that 60 mph was 2000 rpm! In the 6 speed manual's case, it's 3000 rpm, so now I understand why the AT gets so much better mileage. My best recorded figure, to date, is 22.6 mpg. I'm working on trying to first get to the EPA published 24 mpg highway, and then I'll see what I can do to better it. I have heard of some manual RX-8s getting 27 highway; but I'm not yet clear on how it's being done.
  • I'm being advised by a friend not to purchase the 2004 RX8. Can anyone who has owned a 2004 or older give me any advice about it? I really do like the car but don't want to make a big mistake..Gas mileage and oil don't concern me...I'm more concerned about the engine and finding someone to work on it should it need it.

    Thanx! :)
  • ClairesClaires Chicago areaPosts: 1,222
    Since this is the MPG topic, I've moved the posts about buying a 2004 RX-8 to the general Mazda RX-8 topic. Just click the link to continue.


    Need help getting around? [email protected] - or send a private message by clicking on my name.

    Tell everyone about your buying experience: Write a Dealer Review

  • rxterrxter Posts: 2
    04 6sp GT

    20 mile commute - 10 freeway, 10 city.

    Was getting 16 to 17.5 (if staying in the right lane etc.)

    Post Sep 08 reflash - dropped to 14.8 to 15.5 tops.

    Agree, when you run this thing it drinks.
  • Ok, folks I know I'm entering the realm of fantasy, but please hear me out before any profanity leaves your lips.

    So I'm in an argument with a Prius guy at work over the famous Top Gear BMW M3 vs Prius MPG episode where the Beamer got 19 MPG and the Prius got 17 MPG going around racing track.

    My point to my friend at work is that my RX-8 AT, when driven at 85-95MPH in hard Boston Mass Pike commuter traffic where lots of paddle shifting and lane changing is required to stay moving, I've been achieving 20 MPG.

    My friend contends that his Prius beats my 20MPG, but he can't produce any data from anywhere other than straight cruise control drives at high speed that show 25MPG over the 85-95MPH.

    I'm pointing at the Top Gear shows results of 17MPG that the Prius got, as evidence that when you drive a Prius close to it's performance limits, that MPG drops below 20MPG.

    Anyone got any racing or hard driving commuter data to point to? My MPG experience with my 2005 RX-8 AT is definitely a solid 20MPG when doing the fast hard driving 40 mile run from my place in western Mass into Boston, which takes me down 495 and then east onto the Mass Pike. Traffic moves out during my typical segments of the run. I go through two tolls where it's a freak'n drag race off the line most times and I get off at exit 17 before reaching the heaviest Boston traffic.
  • i think you could take any economy car with an automatic and demonstrate that, when flogged, it will get similar or worse mileage to a manual sports car keeping up with it in the highest gears possible.
  • zakallzakall Posts: 1
    I live in Canada and I own a 2004 Mazda six speed. I drive to kelowna twice a week which is around 120km (62 miles). My gas mileage is horrible, I am getting 19 liters (just over 5 galons) to 100km (74.5 miles) or 350km (218.5) to a tank. I dont think the car should be this bad on gas. What do you guys think? Plus when i go up hills the car smells terrible, not like suffer but like oil and gas mix. My engine light turned on for a week but turned off. Any suggestions
  • darkpathdarkpath Posts: 4
    It sounds to me as if your catalytic convertor is failing, and I would suspect that your ignition coils may well be shot too. The mileage you are reporting sound like stop and go mileage, so if you are not doing a lot of idling whilst stuck in traffic, then I think you should definitely assume something is wrong. The fact that your CEL came on says something bad has happened and you need to know what error code was logged before you attempt any further diagnostics.
This discussion has been closed.