How well do you know cars?

Basic vehicle knowledge questions!

1 How often should you change the oil in a mid-size car?
2 The car's dipstick refers to its...
3 When driving down a steep hill what is the best thing to do to help slow down?
4 What does it mean when the car is a sedan?
5 What does it mean if the car is a coupe?
6 In your gauges, what does km/h mean?
7 How many volts is a normal car battery?
8 What is a hubcap?
9 Before electric car starters how would people start their cars?