Here's the Tender I prefer. You can connect two cars to it at a time. They make units to which you can connect 4 vehicles, but I find it's a little easier keeping the wires sorted out and untangled with the two vehicle model. I have several and keep all the cars hooked up. You'll also want to get extra ring terminal connectors and 25' extension leads for each car. It used to be that half the time I went to start a car I had to dig out the battery charger. It now gathers dust. On the Hot Rods, I just open the hood when I park it and plug it in. The NSX has the battery mounted low in the front behind the spare tire and it made more sense to do an externally accessible connector.
Battery Tender
http://www.ebay.com/itm/Deltran-Batt...item4adcd9f472
Ring Terminal Quick Connect
http://www.ebay.com/itm/Battery-Tend...item51bfb38829
25' Extension Lead
http://www.ebay.com/itm/4-Pack-Deltr...item4adde46ed8
