Since couples of weeks, im getting real poor efficiency per refill. I'm only getting 350km per tank wich is pretty bad consideringi would normally get 550km per refill in highway conditon. Does any one have a clue on what should be verified in order to correct this issue. So lately, I changed the spark plugs but it seems like the overall Km is pretty much the same after a week of driving it back and forth...
That's terrible mileage. I get almost 600km/fill (43-45 litres) on my 04 base manual trans. I keep a detailed Fuel Log. That's not highway, either, it's mixed city/rural roads. I would suspect that you have a dragging brake, especially if you don't have any codes.