There is no real way that we know of to earn Hertz Gold Rewards points other than to rent with Hertz. You used to be able to buy them, but I don't believe that option is available anymore.

Hertz Gold Rewards points are not particularly valuable, so even if you could buy them (or transfer from another program), it probably would not make much financial sense. You can often do better on rentals by just finding a good discount and coupon code and paying cash.

Probably the only exception to this would be if you were looking to do a very expensive one-way rental. Acquiring points elsewhere in this scenario might make sense, but it's sort of academic since I don't believe that any opportunities like this exist currently.