My car is a VW Passat Estate with a detachable tow bar (Witter). It works OK on that. The thing is, the carrier is clamped to the tow ball alone - no other connections, so I should think it would do for any car. This seems a bit hairy, but it works.

it fitted our XC90 removable tobar perfectly

No, the cycle carrier fits over the tow ball so you cannot tow anything else.

Unlikely with 3 adult bikes, if kids bike closest to car maybe

No, uses toeball

Carrier fits directly to towball, should fit but if wagon/estate you may not be able to open boot with bikes on.

exactly right. it is very stable once tightened onto the ball

Yes it will.

I have a Jeep Wrangler with a rear mounted spare. You do lose the option of one of the bike slots, due to the spare protruding, but enables you to carry 2 easily.

This is a great product, strong, easy to assemble and does the job perfectly.

Unfortunately, no you can't.

All I did was to use a lock and chain, just as if you were locking your bike up.

Thule 3 Bike Tow Bar Carrier will do the job and still on sale. It may prevent access to boot whilst carrying bikes.