What material is my car made of?

Do you own a magnet?  Use it.

I know the tires are made from rubber and the windows are made from glass, but the rest I couldn't tell you.

I assume that a 300 body is steel.

WOW! I want YOUR paycheck here! NO it is NOT aluminum! You can TELL by flicking the fenders with your finger! ALUMINUM has a THUD type sound and STEEL has a more SHARP sound! Try driving An AUDI A8! iT'S  made from 100% AMERICAN ALCOA ALUMINUM and the total body weight STRIPPED DOWN is only 565 pounds! CHRYSLER patented the name HEMI< but there are MORE HEMI engines out there than you can COUNT! BMW is HEMI< AUDI is HEMI. TOYOTA have a few HEMIS! It refers to the shape of the combustion chambers! My old BOSS MUSTANG was a SEMI HEMI! GL and BYE BYE!

I want to replace the doors, trunk and hood with carbon fiber to make it lighter

What a load of rubbish bet you never do it. Waste of money for little gain.

The trunk and hood are relatively easy to replace. The doors are a witch spelled with a B. You have to disassemble the old doors and put all that hardware and glass on the new ones. 

.......and be sure to get a cold air intake and high performance wiper fluid.