You really should never hope to get a specific model, your lucky if you get the same class of car you booked. Just how rentals work, doesn't make it right, but if you lower your expectations on rentals if you can focus more on enjoying your trip, it really shouldn't matter much as long as it fits your family and your stuff and gets you where you need to go.

Otherwise if you want a specific model/exact car you booked, try Turo.