Ah, the "JR Ewing" Mercedes. One of the last of the real ones, expensive because of the quality of engineering, still built to last. Unlike these new cars with all these gimmicks whose sensors and computers will fail in time, not designed to be durable at all. And horribly expensive to fix.
What good's a galvanised body with a 10-20 year guarantee, if you can't afford to keep the car running due to repair costs?
I turned 16 in January of this year and my dad bought me a 420 SEL Mercedes for $5000.
It is a remarkable car and is really reliable and classy. I was thinking of getting a tent for the windows, however I talked to my dad about it and he said I could do whatever I wanted to it, but he also said that I could maybe try to sell it in 5 years for more than we bought it, since it would be a classic.
So I guess what I'm asking is if I should get a tent and maybe sell it like that later on, or just not tent because I don't want to ruin its value?
I assume you meant "tint"? OK, depending on where you are, unless you need to do it (harsh sunlight), keep it as is. When I buy second-hand cars, I stay away from something which looks like it's been blinged to any degree, including dark tinted windows. A car which looks as stock as possible looks pure and honest.
Mercedes will usually have a greenish or bronze tint on the glass, and it looks great as is. Don't do anything to the car to make it "trendy" or "funky." Trendy and funky do not stand the test of time (sometimes even for a year or two). Whatever you do, keep it stylish and classy.
The one improvement you may want is to upgrade the sound system, but do it correctly. Upgraded speakers in stock locations, plus a good quality head unit. I'm sure a 16-year old like you will certainly appreciate that daily.