This is very low tech and very cheap but this is what I've always done in my SUV.

I take off the front wheel. Load the bike in backwards (so rear wheel goes up towards the front seat, fork is facing the back window, and then using a bungee cord I have attached to the seat belt holder on the rear passenger side, I hook the seat post or top tube and secure it back to the seat belt holder. I usually place the front wheel, between the bike and the inside wall of the SUV. Bikes are very secure. Never a problem. Can easily secure two bikes this way, one on either side.

My SUV can hold 3 bikes, 3 passengers. In that case, since one of the rear seats remain up, it's just a matter of loading the bikes (sans the front wheel) in the remaining space. I usually load the first one rear wheel first, the next one, handlebar first and last one rear wheel again.

There are all kinds of racks you can buy that set inside the vehcile. You can also just buy a piece of wood, nail or screw on a wheel mount and attached your bike that way. Check the internet I'm sure there's alot of this.