Wirelessly posted (BlackBerry8703e/4.1.0 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/104)

The OP might want to consider taking the LIRR from Penn Station out to Long Island, and then picking up a one-way rental with a drop at LGA. Hertz has a location near the Hicksville train station, with a compact showing an all-in price of $70 (using AARP discount). The savings realized by renting the car on the island would more than offset the cost of the off-peak train fare for two; and the OP would shorten the drive by about an hour, compared to renting in Manhattan.

There's also a Hertz location in Ronkonkoma (even closer to Tanger), but I don't know whether that location will pick up from the Ronkonkoma train station.