D22 fuel economy

tubsy · #1 01-02-2012, 07:02 AM

Hi everyone, this is my first thread so be nice.

I'm not sure if anyone has posted this info before, but here it is anyway.

I have just completed a drive from Darwin to Albury and did fuel calculations for the entire trip. I started with a full tank (125L) of fuel and maintained a record of how much fuel was put in at every fuel stop. I also filled up on arrival at Albury.

I have a 2003 STR with ZD30 engine.

My Navara is sporting 265/75 Copper S/Tmaxx at the moment and this varies the figures a little.

The entire trip according to the trip meter in the car was 3670km.

According to the whereis website the trip was a total of 3895km. (yes I plotted the exact route taken)

This gives an error in the speedometer of 6% (ie if the speedo says 100km/h you are actually doing 106km/h.)

So, with a total KM of 3895 and a total fuel usage of 522L, I have done the following calculations.

3895 / 100 = 38.95
522 / 38.95 = 13.4

Therefore the fuel usage for the entire trip was 13.4L per 100km. (if my maths is correct)

A point to note - I was averaging 125km/h for the most part of the trip (a little less in Vic)

I have a Beaudesert 2-3/4 exhaust and the tyres mentioned, but no other modifications to the engine or drive train.

Hope this helps.

scooba_285 · #2 01-02-2012, 07:21 AM

i cant comment on the fuel economy as i have a 2.5 but im pretty sure the speedo is out by 10%, ie. if your doing 110 on the speedo your really going about 100 (give or take)

tubsy · #3 01-02-2012, 07:28 AM

Quote:

Originally Posted by scooba_285

i cant comment on the fuel economy as i have a 2.5 but im pretty sure the speedo is out by 10%, ie. if your doing 110 on the speedo your really going about 100 (give or take)

I'm pretty sure that I have my speedo error the right way around becuase the coppers have flashed me a few times when I've been sitting on 100km/h. But I may be wrong.

mitch92 · #4 01-02-2012, 07:34 AM

Quote:

Originally Posted by scooba_285

i cant comment on the fuel economy as i have a 2.5 but im pretty sure the speedo is out by 10%, ie. if your doing 110 on the speedo your really going about 100 (give or take)

That is correct for the 2.5's, but even that will change if you put on 265/75 as the OP has

robmacca · #5 01-02-2012, 08:14 AM

You can always use the following 2 websites to workout what the % error is, but I found the best way is using the GPS and go for a drive along the H'way at a constant speed and work it out from there. It's also good to "Zero" the trip meter and Zero the GPS Trip Computer and go for a good long drive and compare the 2 when u get back home. U will find that the % error will be slightly different to what it says on the websites (due to tyre wear, etc)

Tire Size Calculator - tire & wheel plus sizing

Miata.net Tire Size Calculator

ST-R STOKER · #6 01-02-2012, 08:30 AM

During Xmas this year i clocked up a few thousand Km's. I worked out the readings for a few tanks.
All in L/100km. 10.2, 9.7, 9.6, 9.7.
I have done the egr and swirl mod, but apart from the all stock standard. I am really pleased with the results.
2005 STR 3.0L

04SilverSTR · #7 01-02-2012, 12:07 PM

scooba when fitting bigger tyres it makes they speedo under read, in my case with my 265/75/16 at 60kmh on the speedo im really doing 65 (as per GPS)

bryan

Oh yeah and tubsy 13.4 sounds about right for the speeds you were doing, if you had sat on 100-105 it would have been better, but still great info!!

tubsy · #8 02-02-2012, 01:55 AM

Quote:

Originally Posted by robmacca

You can always use the following 2 websites to workout what the % error is, but I found the best way is using the GPS and go for a drive along the H'way at a constant speed and work it out from there. It's also good to "Zero" the trip meter and Zero the GPS Trip Computer and go for a good long drive and compare the 2 when u get back home. U will find that the % error will be slightly different to what it says on the websites (due to tyre wear, etc)

Tire Size Calculator - tire & wheel plus sizing

Miata.net Tire Size Calculator

I agree in principle, however; if you are going to use the GPS method, you must ensure that you do so on a flat road with no hills.

The reason being, is that as far as I am aware, a GPS will read distance in a flat plane. So if you were going up and down hills, the distance travelled across the ground would actually be longer than the distance measured by the GPS. Just like the hypotenuse on a triangle.