I have a BUZZ RACK Buzzwing 4 bike tilting and folding rack BRP704 which I was using on my Discovery, but not going to use on the van. It is only 4 months old (I was desperate) so that is available for sale if anyone interested.
Heavy, and I had the altera strada mentioned earlier before, but it finally broke (the handle snapped off!) but I had had it for years.
Think the altera was easier to use, but the buzz one is stronger and more sturdy. The altera slides away from the vehicle, whereas the buzz tilts.
Buzz is much heavier and more bulky to store, but better for the bikes we now have, full on mountain bikes, but I would struggle to get four on - the first 'bay' was too close to the boot of the disco (just) for the wide bars that are on our mountain bikes.
The altera was perfect though when the kids were smaller, and the bikes less 'hard core' !