[Runonfooms]

Hi, I bought my 2009 2L SR i30 new and now have 110,000 km on the clock.  At first the trip computer said a full tank gave me over 600 km, but in the last year this has been reducing at almost every refill, so now it says I get only about 490 km to a tank.  I used to be able to drive from Sydney to Canberra and back without refuelling, but can't do that now so confidently.   The trip computer says my fuel consumption is now 7.7 L / 100 km, whereas it was 7.6 L/ 100km, so the fuel consumption has hardly changed.   Where has 1/6 of my fuel tank gone?  .

[Phil №❶]

Into someone elses tank. 

[Just Rick]

I have never been a big fan of the Hyundai Trip computers,very poor and low quality units,compared to some of the other cars you get these days.

wouldn't hurt to have a full service and diagnostic done to see if something untoward is going on there

[AlanHo]

I would recommend you carry out a proper economy check by brimming the tank, note the odometer reading, then drive the car until the fuel warning light comes on. Now brim the tank again and take the odo reading. Subtract the first odo reading to get the actual kilometres travelled and calculate the actual economy using the fuel used (amount dispensed).

I notice on my car that the distance to empty seems to be affected by how I have been driving the car recently. When I am pottering at medium speeds for maximum economy it gives a greater reading than after belting it on the motorway for an hour.

[Geothe50]

I fully agree with AlanHo. When we picked up our new 1.8l petrol i30 Elite Hatch from the dealer it came with a full tank. Although the trip computer showed an average fuel consumption of 27.4 l/100km (!) on delivery the forecast distance to empty was 615km. Since then I have filled up the car twice and the real average is now 8.7 l/100km - the trip computer claims a much better average of 8.2 l/100km. The distance to empty has gone down to around 550 km. Go figure.

[Runonfooms]

I've had my car serviced at three different locations and mentioned this problem to them, but they seem to think that nothing can be done.  I've tried measuring the km used and it seems to be about right.  By the way I run the car on cruise control most of the time, do you think that uses more, or less, petrol?  I think it uses more petrol as the car accelerates even if I go up a small hill, which I would not bother to do if I was managing the speed manually (I usually drive fairly slowly and cautiously).  However it's the only way I can be sure I'm on the right speed all the time (except when going downhill of course).

[Eureka]

If the tank keeps on shrinking you will be in real trouble.

[Dazzler]

Welcome Runonfooms .. That is an odd one, but what Alan has said is really the only way to check 

[AlanHo]

Unless you are normally a heavy footed driver - the use of cruise control in hilly territory will hurt economy a little.

Only you can make a comparison for your driving style by using a full tank without C.C and then compare the overall economy with a full tank using C.C. In both cases measure the actual economy as I described in my earlier post