If he sees a Mini then he says, "Mini punch and no returns!" - and punches me on the arm.
If he sees a Mercedes then he cries, "Mega mega punch punch!" - punching the arm in time with the words.
It is amazing how many of these vehicles we pass (or pass us) on our 5 minute walk to the bus. One of the Mercedes is abandoned on our road (last road tax 2006, I believe); the house round the corner has a Mini in the drive; I have learnt that a lot of vans and lorries are also Mercedes. All in all, I generally have a very sore arm. Somehow he is always quicker at spotting them and I lose nearly every competition.
So, to rescue myself a little, I introduced the Honda Splat: every time I see a Honda I use my open palm to splat him on the head. Now, of course, he tries to do that to me too, but I'm too tall for him. And he's added in a 'VW dance' and a 'Purr, purr, purr, Peugeot'. This morning he was upset because he has nothing for Audis - he feels something for them would keep him busy (as if he's not busy enough!). Interesting reflection on the state of car sales: he started to introduce more punching for "58" registrations ... but there aren't enough out there.
It seems I am left with a steep learning curve to recognise makes of car from a distance, but a boy who is very happy to beat me - in more sense than one!