Here I will try to introduce some used cars that have depreciated beyond any reasonable level.
Today we have a 2007 Audi S8 going for 3.79 million Yen:
http://www.carsensor.net/usedcar/detail/CU1478626247/index.html?TRCD=200002
Yes you read this right, S8! This luxury monster with a Gallardo engine was priced at close to 15 million brand new. It lost 3/4 of its value in 6 years. For comparison, a stock Nissan GTR will retain about 2/3. Perhaps the horrible fuel economy pretty much labels it useless to an average used car shopper.
Next we have a 2009 BMW 750i going for 3.39 million Yen:
http://www.carsensor.net/usedcar/detail/CU1848411458/index.html?TRCD=200002
OK, this is just insane; the car is latest model and higher range V8. It was registered in 2009 and in 4 years managed to score 74000km... Quite a bit, but does it justify the loss of 75% of its value in such time?
http://www.carsensor.net/usedcar/detail/CU1860838457/index.html?TRCD=200002
OK, here is a piece of local luxury. The 3 year old Fuga 370GT (Infiniti M37) with just 30000km on it lost more than half of its value. This beauty comes with 3.7 V6 from the 370z and will embarrass most luxury rivals from Germany on the road as well as feature wise.
Finally we have a 2007 Mercedes Benz CL550 going for 4.18 million Yen:
http://www.carsensor.net/usedcar/detail/CU1792960226/index.html?TRCD=200002
This will make you roll around like a boss. My favorite depreciation wagon is the Mercedes Benz CL class luxury coupe with amazing interior and Brabus rims. Like the Audi above it has lost 3/4 of its value in 6 years, but it hasn't gone through model change yet. The problem is when it does, you it will look extremely dated and cheap... or will it?
Out of the cars, I think Fuga will give you less problems and grief at the pump, but spending Audi A3 money on a CL is not bad either in my book. Happy hunting!
Disclamer: I am not associated with any deaeler, these are purely finds from a public website. I am not aware or responsible of any malfunction or damage of the above vehicles. Purchase at your own risk if you would like to do so. I will not contact any dealers on your behalf. Links will go dead after car is sold.