About two months ago my lao ban (the one wearing the ring) and I decided to buy a “new” car and we ended up with a 3 year old Nissan X-Trail.
Yes, I know it is one of this SUV things that are evil and burn gas like there is no tomorow but considering all aspects it was the right choice.
However, I thought it might be not a bad idea to make records of the fuel consumption (date, refueld volume in litres, km i made with that and so on) just to ba able and adjust the whole thing a bit.
The first run showed me than 10,3l for 100km or 9,7 km/l (for the gallon and miles stuff figure out yourself please 
).
I got more used to this crap automatic transmission thing (my wife wanted it so that she can drive, she refuses on manual shifting but guess what, we have it 2 months now and she never drove herself till now… 
) and adjusting to the car I cam on 9,8l for 100km or 10,2 km/l.
About 2 weeks ago I heard a strange noise on the front left wheel and with MJB’s help we visited a mechanic. I also wanted to change the oil and do small service to be on the safe side with this used car.
The mechanic finally found a loosend main screw-nut on the front wheel (not sure how you call that stuff, just ask MJB for that) which was a bit shocking but there was no actual damage yet. This teached me to keep up my sensibilaty for unusall sounds and behavior of my vehicles.
Anyway, the mechanic also changed the oil, the oil filter and the air filter. So far so good.
With the first refueling after this mentaniance I immediately recognized a big difference in fuel consumption. The record finally showed 8,5l for 100km or 11,8 km/l with no big difference in driving behaviour or the routes and traffic situations I went through. That’s about 15% less fuel consumption and I guess I still can improve that a bit.
Just my 2 cent…