xg timing

I have a 99 xg that has done 180,00 ml on the clock. It has always given dreadful fuel economy. When queried with the dealer, it was said that it is running fine and the computer does everything so that is the way it will stay. I have never needed to get too involved with it as it has only ever needed normal servicing. Power has always been flat till about 3500 rpm when it takes off. When I put a timing strobe on it today it appears to be running at 25 degrees BTC on idle. My question is, where is the timing triggered from with these and is it possible that it is incorrectly set up in the first place. I don't want to pull this thing down only to find there is no ability to adjust.
Help!
Thanks

u cant adjust the timing. its all adjusted by the computer. take it to a differant hyundai dealer and see what they say. sounds like the oter place couldnt find the problem so they just sent u packing