Test Results are In:
Using two cars, both with 1.0s (since I wasn't sure if running for hours straight might burn the motors out!), one with a stock TOMY cell, and one with a TinyRC.com 150mAh NiMH:
50mAh NiCad
Charge Time: 10 minutes
Capacity: 78mAh
Runtime: 44 minutes!!
150mAh NiMH
Charge Time: 20 minutes
Capacity: 174mAh
Runtime: 2 hours, 14 minutes!!!!!!!!!!!!
That's enough to do 6 1/64th scale 24H of Lemans in a row w/out stopping for gas!!!