Sadly, a class action lawsuit is unlikely to work for this situation. In cases where the damages are relatively low--under a thousand dollars per victim--the main benefit of class actions are to prevent that particular bad behavior from occurring in the future. (Which is why I am in favor of class actions even when class members get small compensation. As the old saying goes, steal a million dollars from someone and you go to jail, steal ten dollars from a million people, and it's just business...)
Here, Hertz will claim that the pandemic caused unforeseeable problems for them--the lockdown drove down car rentals to a tiny trickle, but used car prices skyrocketed since nobody wanted to use public transit. Naturally, given a cash flow from rentals of about zero, Hertz shed its cars into the booming used car market with the intent to buy new ones when things improved. But by then, there was a computer chip shortage making many new cars unobtainable. So...this is why the rental car garages are ghost towns and only very gradually filling back up.
Should they have still continued to have reservations that appeared to be available online? Of course not. That was and is indefensible. But a class action suit can't award appropriate damages to individuals, since each person's out of pocket expenses will differ due to their circumstances--and class action suits are only allowable when damages are consistent across the class members.
A better solution for individuals being screwed by companies like Hertz is to take them to small claims court in your jurisdiction. Easy, cheap, you don't need (and usually can't even have) a lawyer. Argue fraud and breach of contract, have receipts if possible for expenses, and add a claim for money for lost opportunity, vacation days that got wasted, etc. I'd ask for a thousand dollars over provable expenses. Hertz will likely default and not bother to show up, you'll probably get your judgment then automatically.
