hello long time since i have been on here . i have a 2007 sx 380 has 68000 klm on the clock
when i brought the car it was using 13l per 100lms now 4.5 years later says its using 17.1 per 100
service every 7500 klms have just changed air filter no change
would it be the oxygen sensor or something else your help would be appreciated

Could be a bung oxygen sensor, but not normally after only 68,000 km.

And remember there are four oxygen sensors on a 380, two before the third "white brick" cat and two after.

From my experience and reading the two before the cat can make a difference to fuel economy but not so much the two after.

Seeing as it's now six years old I'd check the spark plugs first.

Easy to check the front bank ones, not so easy the rear bank.