I've got an 08 same, 70 for 550 sounds fair to me.
I am a 'spirited' driver and 13 is the norm for mine.
A 500klm fill up for mine would be 65 litres, so you're doing 20-30klms better than I.
On a recent trip from Coli to home, which is 460 odd klms, I filled the tank when I past 650 which gets...