Translation:Come on, faster!
The direct translation is add (加) oil (油), fast (快) one (一) dot(点) son (儿); it does not means "Son, quickly add a dot of oil". The chinglish way of saying is "do what it takes, faster a bit can or not please". I have to agree with you it is not english and inappropriate to rush someone whose car is hungry and is going slow. Before Thomas Edision were born, without other means of light, in times of the moon waning, some people use oil lamp in the dark to study at night. That is why the burn the mid night oil nearing examination period.