If you're talking about a specific El Camino, it would be incorrect to not say "El Camino" instead of "the El Camino." Yes "el" means "the," but "el" isn't an article in English, so it makes no sense to drop the "the" just because of a redundancy: "El Camino was stopped at the light when another driver ran into El Camino from behind" is incorrect, for instance. (Also, if "the El Camino" is a redundancy, then "an El Camino" is a contradiction.

The same is true with the oft-protested "with au jus." Yes, in French "au jus" means with the juice, but "au" isn't a preposition in English, so there's nothing wrong with adding a preposition. If you're talking about a specific preparation of beef (roast beef au jus) then it isn't necessary, because in that case you can assume the foreign phrase is translated directly (as is also the case with Chili con carne). But if you're talking about au jus as a separate sauce, served on the side in its own container, as some restaurants do with French dip or Italian Beef sandwiches, then it's okay to speak of a Roast Beef sandwich with au jus.