Interesting. I didn't catch that. I need to re-watch with subtitles. If so, I'd think it's only one of his business interests, although it is sort of consistent with his owning a garage. Perhaps he's always been around cars in one way or another.
But as I say, he did use to have something to do with a gym. Siân and (I think) Alwenna used to go there, and John always seemed to be around there, and of course, he was all over Siân, trying to get her to take an interest in him, but it didn't seem to be working at that point. He wasn't just a customer at the gym, and he wasn't a fitness coach or whatever (I mean, does John look like a fitness coach...? ).