Re: Where\'s the oil filter???
They serve various functions. The "beauty panel", which many folks here consider to be a hideous blasphemy, definitely dampens the sound of the engine. Especially as heard from outside the car. It also helps to insulate the engine, which is an important consideration for a diesel engine in the winter.
The bottom cover helps deaden sound, too, but its most important jobs are to improve the aerodynamics of the car, and to keep road salt, goo, rocks and debris from messing up the underhood bits. The stuff "down low" is vulnerable to damage and deterioration, and the "belly pan" goes a long way to preventing this.
To remove the top cover: Use a screwdriver to pop out the two circular "plugs". This will expose a pair of 10mm bolts. There is a third 10mm fastener at the rear of the cover. Loosen all three of them and then remove the oil dipstick. The cover lifts right off.
To remove the bottom cover: Put the car up on ramps, and use a T-20 TORX driver to remove the fastening screws.
-mickey