What is a good RC car that you could just pop a new battery in once the old one dies instead of recharging the batteries.

Kyosho make a few nicely detailed mini rc electric cars that run on alkaline AAA batteries.

http://www.review-a-gadget.com/Kyosho-Mini-Z-Racer-MR-01-Nissan-Skyline-GT-R-R32-Electric-RC-Car-RTR-Review.php
http://www.review-a-gadget.com/Kyosho-Mini-Z-Racer-MR-01F-Shelby-Cobra-427S-C-Electric-RC-Car-RTR-Review.php
http://www.review-a-gadget.com/Kyosho-Mini-Z-Racer-MR-01-PT-Cruiser-Electric-RC-Car-RTR-Review.php
http://www.review-a-gadget.com/Kyosho-Mini-Z-Racer-MR-015MM-Chrysler-300C-Electric-RC-Car-RTR-Review.php
http://www.review-a-gadget.com/Kyosho-Mini-Z-Racer-MR-015RM-Lancer-Evolution-Electric-RC-Car-RTR-Review.php
http://www.review-a-gadget.com/Kyosho-Mini-Z-Overland-Mercedes-Benz-G55L-AMG-Electric-RC-SUV-RTR-Review.php
http://www.review-a-gadget.com/Kyosho-Mini-Z-Overland-Porsche-Cayenne-Electric-RC-SUV-RTR-Review.php
http://www.review-a-gadget.com/Kyosho-Mini-Z-Overland-Toyota-Land-Cruiser-100-Electric-RC-SUV-RTR-Review.php
http://www.review-a-gadget.com/Kyosho-Mini-Z-Overland-Hummer-H1-Electric-RC-SUV-RTR-Review.php
http://www.review-a-gadget.com/Kyosho-Mini-Z-Racer-MR-02MM-Ford-Mustang-GT-Electric-RC-Car-RTR-Review.php

There are lots to choose from…