I doubt they have any 'old' cars, but even for a 2017 model it won't be unusual to get the car with 50-60-70,000KM.
That being said, renting directly from Hertz (and perhaps being a member of Gold Plus helps) I can't recall the last time I got anything with over 10,000KM.
I usually pay around 30-35$ per day, including the basic LDW/CDW/TP, but I've never rented during peak times (summer/local holidays) with such a short notice.