I have a 2009 2.4 L Vibe with less than 1500 km and am surprised how low the gas mileage is so far. For the last three 40 L fill ups, I've gotten between 399 and 402 km, which amounts to around 22 mpg (US) or 27 mpg (Imp). How long does it take to break a new car in? My sales person told me I should...