No way $150 yearly maintainance in E55. Hell no ! I own the car only for 10 months and I spent at least $600 without changing tires yet. How about the insurance for a student with E55 ? about $1500 a year ? How about gaz ? this car is not Honda Civic 30MPG. THere is a lot of cost to consider and not only the monthly payment loan $320.
If you calculate the monthly maintainance, gaz, insurance approx $300
And you better hope the E55 dont break because once they break they are NOT cheap.

Airmatic suspension $1000 for both ? Balljoint, arm bash, engine mounts, even transmission fail..... Its not cheap just to keep this car for any student unless rich parents payment for it.