What happens in a car and also with other metal catalysed reactions is that the catalyst eventually becomes poisoned and no longer works. It does not get used up.
In metal catalysis the catalyst provides a substrate on which the reacting molecule is adborbed. During this adsorption the geometry of the molecule is changed making it more reactive. One can think of the process this way. Consider two muggers, the first (the catalyst) holds the victum down so the other one can get at his pockets more easily. The same thing happens in biochemistry with enzymes. They alter the shape of a molecule causing it to be more reactive.
This is true only because the ascorbate regenerates the Phenidone by reducing the oxiidized product back to Phenidone. As a result the ascorbate gets oxidized and used up. If you look in a book such as Mason the reactions involved are explained. If Phenidone were a catalyst there would no need for it to be reduced.Fact is that lots of silver ions get reduced per active molecule of Phenidone
Metol also forms a super additive mixture with ascorbate but is less effective since less of it is regenerated than Phenidone.
Chemists don't hold a different definition of catalysis than other people they hold the only definition.