kiwimeat

Well I’ve had my RX-8 two weeks. As of this morning it has done 705kms (been too busy at work to do much driving beyond the necessary). It’s been great fun – except for the ********* you appear to attract every second to third set of traffic lights (especially at night). However, nagging away and just diminishing my enjoyment a tad is the thorny issue of fuel economy.

I’ll start off by declaring that I bought my RX-8 being fully aware of the fact that a rotary engine – even the new Renesis – was never intended for fuel economy.

However, my extensive research included the long term economy information posted up by many of you. So my expectations were in the 12-15l/100km range for long term economy.

Now to be honest with the exception of the first tank the vast majority of my driving has been inner city commuting often in peak hour so I am not expecting miracles.

See attached image for my calculations for my fuel “economy”


I don’t personally think I have a lead foot, nor do I think I have been overly “fanging” it. There have of course been some experimentation and demo runs to friends and families. However, that said, in general I am keeping rev’s between 3-4K. Have only exceeded 5K on a few occasions - mostly accidentally to be honest and even then staying below 7K (as per handbook).

Questions

1. Can I expect the economy to improve as the engine runs in?;
2. Am I being overly anxious and I should just “get over it”?; or
3. Should I be concerned and making a big issue of it with my dealer?

I am intending to raise the issue at my 1000km check up and will ask for confirmation of the ECU Flash version – G is the latest I understand.

Cheers

takahashi

Answer:

1. Definitely yes!
2. I think you should just concentrate on all the things about the car except the fuel level at present. Also concentrate to run in your car, too!
3. I don't think so, I quite honestly think your car is G flash but good to check just in case.

The report from other guys is that best fuel economy is when you run in the engine after about 5000km. I hit recently with 50:50 city:highway driving of 11.8L/100km and next tank is 12.5L/100km with a lot of fang. Now I am average about 12L/100km with 30:70 driving.

CMac

Kiwi,

I was just thinking about this topic last night as i filled up. the car came with 1/2 a tank and i filled it up and have just gone through this tank and measured about 18-19L / 100km. I'm now upto 460km

all this has been peak hr to/from work only a few squirts upto 7k with 95% of gear changes around 4k & with only 1 extended drive not in traffic.

this weekend i'm going to take a drive up or down the coast or to the blue mountains to get a few hundred km's closer to the magic 1000km!!

I've already noticed the gearbox is a little less notchy and i've only stalled it once in traffic!! I know i didn't need to worry but for some reason i had a silent prayer.. do not flood on me in peak hr :o low and behold she purred back to life.

I'll note my fuel consumption but not worry about it till i have a few '000 kms on the clock.

LittleJohn

Yes.. your fuel economy will get better. I'm at 20000kms now and I get about 13ish L /100km pretty consistently, and that's with mixed driving.
The other things I noticed was
1. After a service, if your PCM has been flashed, the fuel economy drops quite dramictally, but it appears the PCM "re-learns" your driving stlye and becomes good again.
2. the grade of petrol makes a HUGE difference. eg. Over tha pst week or so, Optimax has been unavailable, so I filled her up with a tank of regular unleaded with a bottle of octane booster for good measure.. But the tank only lasted just over 400kms and she was pretty dry.
I've since filled her up again but with Caltex Vortex, and the fuel warning lamp only just came on at 390kms which means that I should be able to get at least another 80kms out of her.
3. driving like a granny really doesn't help fuel economy all that much.. i.e. if you shift at 3k/4k rpm vs 5k/6k rpm, the tank goes about the same distance. I only notice a dramatic change when I do numerous 9k / "beeep" shifts in one tank, maybe 12 or more..

Just my obsservations.. no scientific studies here....
hope this helps

Wildcard

I'd re-attack the issue after another 1000km. If you haven't come below 15L/100km by 2000km on the clock, there could be a problem.

The ECU is designed to run rich initially to prolong engine life. It will gradually lean out all the way to 20000km. I have also found that changing fuel makes a difference, as the ECU is a learning ECU.

dracoMJB

My average for the first 5000km was about 11.7 and my next 5000 was 11.8, maybe it was more because the majority of my driving for the first 10,000 was highway 50km+ trips plus some 400km+ highway trips that the extra richness for the first .

My current average for the last 2000km is at 11.97 but most of that has been short 10km 60kmh-80kmh trips (thankfully not stop start though). My overall average (including the advanced driving day that peaked at 18.9L/100km) is 12.09L/100Km.

takahashi

My worst fuel consumption was the morning of 16 Nov (32L for 96km) and also lost 400 ml of engine oil.

Despite using Optimax with Octane Booster to protect denotation.

I think it is something to do with the 75% time of WOT at Sandown Raceway :p

DCD

My RX8 is the worst car I have ever owned in terms of fuel economy, including a 156 GTA (3.2 V6), and a 170kW@wheels S15.
I drive about 70%-80% motorway, and I only just get 380km to a tank. I can't get 400km, the petrol light comes on at about 330km to the tank. Or about 50-52 liters.
I don't think I have that heavy of a foot, I do like to drive my car, but I don't thrash it all the time. I have done about 10,100 km in the car, and at first didn't care about the fuel economy, but I am starting to get more and more worried about it. To be honest, if I knew the fuel economy was like this, I would have thought twice about getting one. At the very least I would have liked more power for the economy that I am getting. My S15 was only ever this uneconomical when I was driving at trackdays!

takahashi

DCD of course you have not owned an HSV or a Dodge Charger in your life :p
330km to 50-52L = 15-16L/100km is about right for congested motorway plus city drive... am I right?

I am telling you I get 450-500 before warning light but I don't have traffic in my motorway (100kmh in cruise control all the way)

I think the best way too look at it...

1) it will get better.
2) get the latest PCM flash
3) pray to god that oil prices falls back to 30cent/barrel

DCD

Haaa yeah but thats why I shy away from big V8's as well, I don't want to own them!!
I remember one trip for snowboarding I went with some friends, and one of them drove his V8 Explorer, that thing was getting about 17-18l/100km, on the open road!

This fuel economy, is what I'm getting after a flash, and a service, before I was barely getting to 330-350 before I would have to fill up.

Problem is I drive in excess of 50km a day, 20-25 km to work (but this is cut down now as being responsible I car pool now ), then back, as well as sports commitments, 6 days a week!
I almost need to buy a hack to drive around, in but then I always say whats the point on owning a nice car if you arn't gonna drive it. Its not like I ever have to leave my car anywhere dodgy during the week so I enjoy driving it.

I guess another thing is like I was saying above, for the amount of fuel the car drinks, I wish it had more poke to go along with it! Oh well......

CMac

I'm not too concerned about it at this stage however i'm planning on it getting worse for a few tanks after the 1000km service as i'd like to make sure my buzzer works okay.

takahashi

DCD, that is the sole reason I sold my sport car for the RX-8 but keeping my old Camry V6!

I will never get down to 7.4L/100km for RX-8 in 110km/h no traffic highway. The best is 10.8 @ 105kmh.

That is precisely why my RX-8 is my track and weekend car... and I am missing it a lot!

DCD

takahashi, so you got sick of the big V8 consumption huh? My dad is into his big V8's, when I talk to him about them it sounds like they are terrible to do with fuel, but he pretty much keeps his fun cars, as fun cars, and only really drives them on long trips/weekends etc... Its a pity that where I live I don't have room to have another car, otherwise I would like to think about getting one.

timbo

If you search in this forum you will find my long term fuel economy charts. Reminds me I should update for the last few 000k

Basically, don't buy or drive an '8 if you want economy! This engine gives performance and the fuel economy is generally consistent with other cars giving similar performance. Yes, you can get better economy from a GenIII V8, but not if you are pressing on -- and they use more oil And the 8 is, well, let's face it, a joy to drive in a more spirited fashion, even on the daily commute.

Economy does improve over time, and a bit with later flashes (I won't swaer on that) but the long-term best average is going to be pretty much as Mazda specified.

If you want to improve your fuel economy, I'd suggest the following:

1. Don't drive the 8, except on weekends
2. Definitely don't participate in track days (I can vouch for Taka's experience .. 26L/100k when went to Wakefield :o
3. Always drive at 3,250 rpm or less, as that's when the second intake port opens. Actually, that's just on 110kph in 6th, so allows a thrifty cruise, as some people have shown.

The trouble is, options 1,2 and 3 make the 8 a really boring car. :p

tonym

Yes, when new the fuel usage is a little higher (13+Litres/100Km) and then improves a bit (11-12Litres/100Km) as it gets more Kms under the belt. It depends on how much "fun" you have

I can speak as one who "used to have" an '03 RX8 which got up to nearly 40,000Kms and averaged around 12-13Ltrs/100Km, and now has a new '04 RX8 with 2,000Kms on it and currently doing 13Ltr/100Km average but treating it gently I do around 150Kms+ a day on an interesting driver's road, generally having much fun! This is what this car is about!

This is not a car for fuel economy, it is for the fun! I have had a couple of XR8 V8s for the same sort of fun driving, just different ways of doing it.

Fun car + Fun driving = using much fuel

If you want fuel economy, get a boring car without the fun, get a Charade!

Cheers,

Tony.

NickG

16,000km and I still hovver between 14.5 and 15.5 l/100km based on my daily commute, which is a mixture of 80-90km/hr clean sailing and bumper to bumper Sydney snarl. I've given up hoping for better, but fortunately our little car has so many other compensations...

spaldo

I've only done about 3500km and round the suburbs fuel consumption is about 15.5l/100km. On a country trip, averaged about 10.5l/100km. Interestingly, Taka our V6 Camry doesn't have much better petrol consumption than the 8, but it doesn't take premium.

RXE16T

You guys aren't driving the 8 the way it was intended to be driven...... 14-16L/100km?
I average 17.5-18L/100km because I drive it like I stole it. :D

sco

IIRC one of my first tanks was 17L/100 which was a lot to do with not maintaining a consistent speed, driving in unusual gear/speed combinations and short trips.

I do an inner city commute to work and after 13000k's I'll average around 15L/100 and this is keeping it under 4K rpm when cold (which is most of my trip to/from work). On a recent long distance trip I averaged 10L/100 cruising at 3,500RPM for 700kms - so I know I can get good economy.

Short trips is what's killing your economy.. the rotary drinks a bit at idle and also cold starts seems to drink a fair bit too. Do some good runs up or down the coast and if I'm right you'll see some big differences.

kiwimeat

Thanks for all the replies.

Took Taka's advice - decided to stop trying to nurse it around and drive it like I want to/it deserves to be (within the limits of running in of course).

So it's full steam ahead and damn the torpedo's.

Just took the long way home from the Video Shop - 28 kms instead of 4!

Anyway I can always look on the bright side of fuel economy- at least I don't drive a Porsche Cayenne!

sco

Yep... the RX-8 sure gives new meaning to driving the long way home... via Mt Nebo is always great!

kiwimeat

Isn't that quote from the Lancer advert?

Who would steal a Lancer? Beats me how Mitsubishi continue to make the car uglier than the previous model.

RXE16T

Not sure..... don't pay too much attention to TV ads featuring Mit-****-bishis.


If it's worth something, it's worth stealing..... in this case, maybe $500 for their efforts, but a bit more if it's an Evo. :D

labrat

It takes time to learn how to drive the car. 11.5L/100km is quite achievable around the city, keeping up with the traffic and enjoying your driving. Getting under 10L/100km on a trip is also easy. You don't have to sacrifice "spirit" in your driving, but you do have to learn when to display it. When I first got the car, I rarely used 6th gear. Now I use 6th like I used 5th in my previous ride. To me, driving is all about smoothness.

Gibbo

OK I have read this thread and can not see how anyone is getting 12l/100km, I consistently get 16 - 18L/100km. My last tank was 16.6. I have owned everything from HSV's through to now an 8 and it is by far the worst economy ever (including trackdays in the HSV).
However I believe that if you bitch about the petrol then you can't really afford the car anyway (this is not aimed at anyone in this forum at all it is only my feelings). If you are concerened over fuel consumption then go buy a diesel, I bought this car to drive, not to keep log books like my grand parents and say "oooo this week I got 35 mpg", please forgive me if this seems a little harsh but you should be driving the "Bits-a-shitty" Lancer if you want fuel economy, I personally love the fact that every day I drive this car I get days like today......
Had a meeting at a hotel in the city, went to the hotel that I thought it was, when I pulled up the valet said "man nice car" I replied with a thank you and then asked him whether I was in the right place, answer was no it was their other hotel across darling harbour. I proceeded to the other hotel and pulled up at the concierge, same comment from this guy, he took my car and parked it, after my meeting he bought it back around the front and once again commented on the car and said that this was the only car he had ever driven where someone asked him to stop so they could get a photo.

For me that is why I bought the car, performance, unique looks and one hell of a fun drive.

As I mentioned ....Fuel economy....bahhhh........ you can have your facts and figures.