Yes and no. On the first build, only the sub box and the side compartment were secured to the car, but everything was all a one giant piece screwed into each other so it couldn't move. However, I don't think it would have done very well in a rollover.
On my current one (still more of an idea that reality yet), I want each section an independent piece that can be added, remove, or altered without having to remove any other parts. With that, I'll need to hook everything down independently and I'm trying to make it strong enough so that nothing will start rolling around inside the car if it goes upside down. Just a precaution that I hope to never test, but I'd rather not get killed by my own build.
I haven't figured out how to secure the bottom part down yet. Still thinking and open to ideas.
Hatch Nation #13 : Rally Revolution #13 : ROTM Jan '13
It's Bryan, not Brian
RSVT-170 Build in Progress
Derusting Rusty Build in Progress