Have you ever shopped for a used $100k+ car? The majority of them lose 30% of their value once they start rolling off leases in mass (around 3 years used). Once they hit 5 years old they are into the 60% - 70% area. I'm not talking special edition rare 911s obviously. I'm talking your general luxury vehicle.
Here goes a 6 year old (5 by model year) S550. Probably $120k+ new. Close to 70% depreciation.
2015 Mercedes-Benz S-Class S 550 | eBay
Don't blame it on the miles either because I'll show you 2015s with lower miles in the $40k range.
Here's another example. 2015 Range Rover. Retail also over $120k. 50% depreciation. If it wasn't a signature edition it would be more.
2015 Land Rover Range Rover AUTOBIOGRAPHY Supercharged | eBay
There's a number of factors here.
1) $100k+ cars are generally expensive to maintain/repair. So price has to come down considerably for someone to feel comfortable having enough extra cash to fix problems.
2) people who can truly afford these cars lease them. they don't buy them and certainly don't buy them used. so once these come off 24-36 month leases Mercedes/Range has to dump them for what people are willing to pay. And when people who have money don't want them used....they have to fall a considerable amount before it reaches the next class of people who can afford them. Hence regular Joes being able to pick up a fairly new S63 AMG and floss in it without a $2,100 payment.
Next time you're in the Dupont Registry or looking at $250k+ Rolls/Bentleys and Super cars up for lease...look at the advertised terms. The leases stretch out for 5 to 10 years. This is not only to make them more affordable on a monthly payment but also to keep the used market from being flooded.
Certified Pre-Owned is a way to fight both #1 and #2 and try to capture back that people with money market.