Mechanic lines run on engines, spark and things that need looking at — a trade whose vocabulary was apparently designed by an innuendo committee. They land best with people who know a torque wrench from a breaker bar and will respect a correctly-named part.
The check-engine-light material is the standout: a warning light for feelings is a genuinely good metaphor, and the trade earns it.
Mechanic material earns its keep through accuracy: name the part correctly and the trade audience upgrades you from civilian to worth-talking-to. The check-engine-light conceit — something's lit up and needs attention — is the category's genuine contribution to romance.
Garages during the annual MOT small talk, car meets and trade counters are the venues. The car lines serve the enthusiast side of the same garage, the electrician and plumber lines cover the neighbouring trades, and the full workshop is in the occupation collection.

