[VaerO]

When I first got my i30 I was getting a reading of 511km per a full tank of fuel, now a days  however it's dropped to about 470 - 480!! Why would this be?

[AlanHo]

It is only a crude indication calculated from the fuel level in the tank and the previous recorded trip economy. Unfortunately the fuel level sensor is not linear. On my cars when I have brimmed the tank to the filler neck the fuel gauge will continue to show full for many miles and will initially fall quite slowly - speeding up as the fuel level falls.

On my previous i30 if I filled the tank until the pump clicked off -  the car fuel gauge would then show full and the DTE would give a reading. If I then added more fuel until the tank was brimmed to the filler neck (sometimes as much as 10 litres) - the distance to empty reading did not change - which suggests it ignores fuel added above a certain point.

What you will find is that as you use more and more fuel the DTE will slowly correct itself and show a more accurate forecast.

I pay little regard to the DTE reading - until the low fuel warning light comes on.

[rustynutz]

VaerO, perhaps your style of driving has changed (from when you first bought the car) and you're now using more fuel. The trip computer is probably just taking that into consideration.... 

[Phil №❶]

Because it's not a Diesel. 

[Doggie 1]

It is only a crude indication calculated from the fuel level in the tank and the previous recorded trip economy. Unfortunately the fuel level sensor is not linear. On my cars when I have brimmed the tank to the filler neck the fuel gauge will continue to show full for many miles and will initially fall quite slowly - speeding up as the fuel level falls.

On my previous i30 if I filled the tank until the pump clicked off -  the car fuel gauge would then show full and the DTE would give a reading. If I then added more fuel until the tank was brimmed to the filler neck (sometimes as much as 10 litres) - the distance to empty reading did not change - which suggests it ignores fuel added above a certain point.

What you will find is that as you use more and more fuel the DTE will slowly correct itself and show a more accurate forecast.

I pay little regard to the DTE reading - until the low fuel warning light comes on.

 
Good explanation.

[VaerO]

Hmm, I do seem to always win the race when taking off at traffic lights  But I swear I'm not going that fast! I always look to the right before taking off to make sure there's no loon running a red light etc.. but still seem to get ahead of most other cars. Maybe it's because I'm a P plater? 

My usual daily drive to work and back is a very short one, work is literally 3 minutes up the road (Reason I didn't get a diesel although I would have loved the extra torque)! The trip is also very hilly (Cars usually in 3rd gear most of the trip and mostly in 2nd to get up my street), I'm pretty sure my street is the steepest street in Wagga, could all this count to the reading? If all I do is drive to work and home everyday for a week my L/100 is around 10 - 12. When I go for drives around town on the highway (Speeds between 80 and 60) with friends it drops to about 9 - 10 and when I drove to Sydney and back it dropped to between 5 - 7.

Also when filling I always stop when the pump clicks, I've never "brimmed" the tank before.

[Phil №❶]

No, if the driving you are doing each day is the SAME driving you've always done, then the kms should not vary by much. The only reason for kms to alter is for something else to alter, like harder acceleration, altered driving style, weather temperature, fuel quality, engine air filter, ignition, valves, tyre pressures etc.

As already mentioned by Alan, the figure stated at fill up is at best only an estimate, once you've traveled 100k's on that tank of juice, the computer should have made a more accurate estimate, based on your current driving style.

Do try to give your car a decent run occasionally, to keep moisture out of the engine oil. Water in oil builds up when the engine does not reach operating temperature multiple times, the fuel you're burning is a hydrocarbon, after all. Check your oil after a run, as the water evaporation will alter the level on the dipstick. Water and oil long term, cause sludge, which is bad for engines.

[VaerO]

Me and friends go for a long drive at least once a week for that sludge reason, does changing my oil regularly also help prevent this?

[Phil №❶]

Yes, but how often are you doing this 

[VaerO]

My oil was change at the first 1000km service and I plan on requesting another oil change at the 7500 service coming up in about a month.

Edit: While we're on the subject of fluid changes... When should I ask to get my trans, coolant etc.. fluids changed?

[Phil №❶]

Basically, they are changed at the indicated service intervals.

The only people who have changed their trans oil early have been those who live in a freezing climate AND had difficulty selecting gears when cold. If yours are smooth, then no need to change. From memory, not a good idea to change it yourself as there is a trick bolt int there that you don't want to touch. I think Rick-p knows about this, perhaps he can refresh my memory.

My question re oil changes was also to suggest that anything less than 7500k's would simply be a waste of money.

[VaerO]

I had a look at my oil on the weekend and although it was high it was pretty dark in colour almost a burnt caramel colour... Shouldn't oil be a golden syrup colour?

[Phil №❶]

Yes,  but during use, it will pick up some ash from combustion by-products. As long as there is no separation caused by water in the oil, all is well.

[TheReaper]

Yeah, that is normal. Its just going from golden syrup to burnt toast (black)

[eye30]

When I first got my i30 I was getting a reading of 511km per a full tank of fuel, now a days  however it's dropped to about 470 - 480!! Why would this be?

To rule out change in driving habit why not clear the memory and start from a fresh.

To clear it you will need to disconnect the battery for I think 30 minutes to 1 hour.

It will then re-calibrate based on your current driving style

[Geothe50]

When I first got my i30 I was getting a reading of 511km per a full tank of fuel, now a days  however it's dropped to about 470 - 480!! Why would this be?

I have noticed in our car that the DTE varies - as expected - according to the driving style. Let's say you start on 530km DTE and then go on a long, constant speed Hwy drive. The DTE will increase and could reach 650km. That means after having done 320km the trip meter still says 330km DTE. Conversely, if you only do inner city short distance driving the DTE will decrease.
As others have suggested you should not pay too much attention to it; but when DTE reaches 70km I usually fill up again