- Fuel Injector Cleaner after EVERY FILL UP = Overkill for sure
- Checking and maintaining high tire pressure Presuming you mean the correct pressure, yes
- I clean the engine (moving parts) of any gunk, oil or whatever might cause the engine to work harder. Yes
- After EVERY oil change, Oil stabilizer right in. (I got lucky and got a box of Oil stabilizer/Engine protectant for about $2.75 each. The only thing that goes in your engine is oil ... nothing else
- Trying to drive no more than 20 over the limit and making sure that I shut off my engine during long idles. I also try to make sure and maintain speed instead of stop and go. Steady is the key here, smooth and soft accelleration too
Clean air filter too, and an exhaust mod will help mileage. Turn off your air in the summer, use windows or just blower vents.
600km for 50l is pretty good. My wife gets between 600 - 700km for her mystique but then she drives 200km for work each day which is 100% highway.
Personally I wouldn't worry too much at 600km/tank.
IF you're trying to save money then the difference of 600 and 700km per 50L fill up (at $1/L) is only $0.01 per km ... or $7/tank maximum. Even whent it was $1.40/L we figured out a difference of just over $0.01 per tank.
