hatchback clip-on type? Wouldn't put one on my car! Wouldn't put my bike on one either.
I once got one that clipped onto the boot and when it was correctly mounted it didn't seem stable enough even without the bike on so it went straight back, i certainly wouldnt' have been happy with my bike on it.
They also aren't great for the bodywork of your car.
consider a towbar mounted one, that's what i've ordered for my new car. they're apparently a lot more stable than hatchback clip-on type.