How does Boris' ability work?

[Searanox]

It says something along the lines of "automatically repairs damaged kart".

I tried that in the demolition derby mode and it doesn't seem to make any difference. Then I tried it in the "witch's giggle" track, as there's a lot of narrow passages and damage happening... nothing. I ran the whole race avoiding the repair kits and the kart never repaired itself at all.

Is it on a timer? Is there something I'm not understanding?

[090psx]

i remember the kart is actually repaired when you attack other cats.