My wife and I have many different bikes and transport different ways. Both vehicles have Yakima racks with Steelhead mounts, we also have a hitch basket that I've bolted some bike tights on and I've made a small mount for the interior of the vehicles.
I've since moved the mounts inside of the basket so the handle bars don't stick out so far.
I used an aluminum door threshold to make this thing. It'll fit 2 road bikes (or one mountain bike and one road bike-mountain handlebars are too wide and hit) and fits in our 4runner and subaru. I drive long all over the state for rides and don't always like the bike up top or outside of the vehicle for different reasons.
I've had 4 bikes on the Yakima rack with no problem, unless you're on a trail and in the trees.
My old truck had mounts for 8 bikes.
Roof rack on the trail.
This is a mix of roof rack and hitch rack mounted carriers.