I've got an extension that is longer than the car using those same plugs. It's useful for testing brake lights, etc on the back of the car. Large alligator clip attachments go on the battery end of the extension, and a logic probe (or whatever) attachment plugs into the other end.

I'm sure bullet connectors function perfect. These connectors are convenient though because they're designed to be quickly and frequently disconnected from R/C car batteries. And they can take some amperage.