Who\'s good at working out MPG?

[carlbrainiac]

I would like to know roughly what MPG Im getting with my FD3. I know I know I probably dont wanna know lol. But I would just like to know just how bad it is lol. Unfortunately my maths skills are awful.
So I was wondering if anyone could help me work it out.
 
This info is based on average driving. Some longer journeys. Some short journeys. Some traffic driving. Some driving conservatively. And of course some ragging it. So this full tank has had a good average use.
 
Here\'s a pic of the fuel guage. So wasnt completely empty. But as far as I was brave enough to empty it and I will probably never let it get this low ever again:-

 
And my trip computer distance that I havent reset since I last filled her right up:-

 
Oh if only that trip computer was in Miles. Then 204 miles isnt that bad lol. But I am guessing as it has Km beside it that the trip computer and odometer are still in Km. Eventhough the speedo although still says Km has been converted to MPH.
 
Then immediately after taking those pictures I was actually at the petrol station and I put in £78.78p of Tesco\'s momentum 99 which was 55.91 litres at 140.9 P/L

[Dehs]

Thats about 127 miles, which isnt too bad... youve still got a fair amount in the tank looking at that... as long as your fuel tank isnt full of crap, you should be good to hit the orange light.  You can get about... another 30 miles or so if your careful outta that tank, so youd probably get about 150 miles at least outta that much fuel

[Will66]

Right, here\'s the method I\'d use!

First you need to know the number of miles you\'ve driven since you reset the trip when you filled up.  There are 1.61 km to a mile, so if you know the number of kms you\'ve done then you divide that figure by 1.61.

In this case

204.2/1.61 = 126.83 miles

From there, you know how many litres of fuel you\'ve put in to the car.  In this case 55.91 litres.  There are 4.55 litres in a gallon of fuel so to get the number of gallons you divide the number of litres by 4.55.

55.91/4.55 = 12.29 gallons of fuel

To get your mpg you divide the number of miles you\'ve driven by the number of gallons.

126.83 miles/12.29 gallons = 10.31 miles per gallon.

Quite glad I have an RX8 now!  That sort of figure is what I get from a track day!

[carlbrainiac]

Bloody hell that is bad. I thought 25 mpg was bad from my Subaru lol.
 
I didnt even know there was an orange light that comes on when low on fuel on this car. Do all Rx7 FD\'s have that? And when it comes on how far roughly would you get with it on? Obviously I would never try it but just in case it ever came to that and I was desperately trying to find a petrol station. lol

[Dehs]

Depends how you drive it.  Mine ran for... 20 miles of light usage once the orange light came on.  There isn\'t anything bad about running it lower on occasion as long as the fuel tank is clean, otehrwise you suck up all the crap, and things start to go wrong from there.

Not sure if all FDs have the fuel light, but an easy way to tell is turn the ignition on, but dont start the car and check what dash lights come on =)

I know that the FD can only max out at about 20mpg on light usage by old ladies xD  But the fuel cost is worth the sheer joy of driving the car, every time i get into mine i cant help but go all smiley.

The best way to check your fuel is to drive how you want, and see how long a tank lasts you.  I mean, the way i drive, if i can manage on a tank a week im happy =)

[carlbrainiac]

And is it normal for the exhaust to pop and bang every now and then? And it stinks of petrol too. But one of my mate says this is normal. And another of my mates says it sounds like its over fueling and that I should get a map check done to make sure it isnt dumping a load of unused fuel in.
 
Thoughts?

[Dehs]

Erm, what mods are you running, and have you had the car professionally remapped?

I know that if you have decatted etc it will mean your car needs a remap asap, otherwise the engine is running lean.  On mine, before i stuck my PFC in, it would backfire like mad on every up/downshift, but i do think my plugs are on the way out...

I would get a PFC as a first prio, then go get that mapped at a specialist to ensure you dont break anything...

[carlbrainiac]

Well the previous owner put a new cat on it as he always struggled to get it through the emissions test on the MOT. But he said now it gets through. Just. And I dont know if it has been remapped or not. All I know is I believe it has a K&N Panel air filter as a replacement for the standard one. Though I havent actually taken the air box apart to see if this really is present. But what I definately does have is a Baileys Dump Valve. Dont know if that makes any difference. And an HKS cat back exhaust system. Well basically back box. And it doesnt back fire badly. Just say when Im parking up or in traffic and just using light throttle then off again sometimes it just does a lil pop pop. Always at very low rpm after backing off. Not as if its at high rpm going BANG BANG or anything lol.

[lee mills]

Might be worth checking wether your odometer measures in km or miles as i know when i changed my speed from km to mph it also changed  my odometer from km to miles:Thumbs-up

[carlbrainiac]

How would I check this?

[lee mills]

drive a predetermind distance in another vehicle then do the same in your fd and see if its the same would be the easiest way

[RobMatthews]

sure when i changed mine it goes to miles to.

take a couple mile drive with a mate both of you reset your counters and he follow you for two miles see that they match up at the end.

if your only getting 10mpg out of a standard car something is not quite right!

[Dehs]

Yeah, thats a little low, but if he\'s running rich coz of a badly mapped ecu for his current mods, it would explain the low figure...

Im not 100% sure about this, but it could be a result of the ecu map shoving excess fuel in at low speed, which then pops.  I still think the best you can do is take it to a specialist and ask.  Its probably nothing, but for piece of mind, and better economy/performance its worth it...

[bigdawg]

not to hijack the thread or anything but why do people always say dont run low on fuel because you start to suck up all the gunk... i mean, isnt that why the fuel filter is there?

[Dehs]

Yeah it is, but why shorten the life of something prematurely, or risk something like that at all w/o a good reason