I read somewhere, about a year ago, that a scorcher was someone who could put in a certain average in a race. I think the distance was 20 miles in the hour.

You also need to wear your peaked cap backwards!

I also think it is a good term, but again we are misappropriating an older word with a specific meaning. But that is the evolution of the English language.. just look at the change in meaning of the word 'gay'..