The description says the income depends on how many cars are crashed in the game during the week. Does it mean that making cars explode (by shooting at them) will increase my income from the junkyard?
The Car Scrapyard gives you $150 dollars for every car you destroy. You do not need to take the cars to the scrapyard itself.
This is paid out each game week on Monday morning (00:00).
I've just tested this by blowing up two cars on the highway at 23:00 on Sunday. My earnings email for the week came shortly after indicating I'd made $300.