Ground loops are created by grounding say.... battery to chasis then chasis to block then block to frame, etc. The point of using a bus (similar to what I mentioned above) is to avoid that very thing. The common ground becomes the bus (not the battery) and is installed parallel to chasis, motor, and battery, alt, so that loops are not created.
Aside from the bus, many audio shops carry some pretty large negative battery terminals that are used to do pretty much the same thing. The limitation that I see with those, is that you're often limited on the gauge of wire you can use.