I bought a new battery pack for the White Tiger Turbo Buggy, along with rechargeable 9V batteries. It's fantastic, we drove for over half an hour, vs the 5 minutes the old pack could still muster.

Only now have I discovered that what I always understood as a child to be the "turbo battery" is most likely only responsible for the radio (matching the 9V in the controller). After a lengthy session the 9V reported as fully charged almost immediately. Maybe I didn't need to invest in rechargeable 9V batteries afterall, oh well.