I've just bought a '13 Sonic LT 6/spd Auto 1.8. Just curious on the actual MPG. I started an average about 18.2 in the city. I've reached up to 20.5/city and I am at a stand still. Now I have only had it a week so I'm not sure if I should wait until I reach 500 miles or is this normal. I'm averaging about 60-70miles per quarter tank..eek.