i don't believe it's necessary. that's a request you'd make when checking in as specific tables are not generally reserved for individuals, but the ratio of cars to tables is so large that it's not something i'd worry about. i've never heard of someone making an ADR and not getting a car. the 'rumor' used to be that walkups would be the ones more likely to get tables (of course that may have well been the case when space for walkups was reserved).
there are a few reasons why someone might opt for a table, but that's their concern. if getting a car is yours, i wouldn't worry about it.