If new - the best bet is to call your local dealers and talk to them. I'm aware of many dealers that haven't turned a unit in 3 weeks now, they need the business and likely will be willing to give you a great deal because they need a move inventory.
If used - I would wait until some of the auction houses re-open and try bidding on a car. If that's a little stressful (it can be) then I'd look at Carvana, Vroom and Shift (depending on your geographic region).
From there I'd look at local used car dealers - don't let them game you or try - Carvana/Vroom/Shift all recondition to a Lexus CPO (Certified Pre Owned) standard you just can't legally say that if you don't have the approval from the manufacturer (another weird quirk) - you should be able to find a like for like vehicle between Carvana/Vroom/Shift & a local dealer.
Whoever gives you the best deal take it, but both online and in-person dealers are marking down inventory.
If you can wait a few months, the prices will be lower with all those vehicles come off-lease.
Keep in mind that with Hertz filing for bankruptcy that other rental car companies aren't that far behind, so there could also be a massive influx from those folks needing to liquidate some assets.