The discussion has arisen in the past regarding having the bellypan on or off the car.
I'm pro-Bellypan. The car came from the factory with it, therefore it was designed to be part of the overall system for whatever reasons.
The Bellypan is prone to abuse. Some folks don't have one because it has been destroyed over the years & hasn't been replaced. Some don't want one.
Here's a recent example of why a Bellypan is a good thing to have attached to your undercarriage...
I had the 500E inspected at a local service garage by a second-generation mechanic who is probably the only guy I would let touch my car. Our fathers were peers.
Upon checking my power steering level, we got carried away in discussion. The car checked out fine after a thorough inspection & away I go.
After driving, I always park my car in my garage & lift the hood to let the heat dissipate. I noticed the black knob that secures my power steeing fluid container cap was missing!
I'm leaving town for over a month. I leave him a phone message to check around his garage for the part. I get back yesterday & check with him at his garage. No luck. He feels bad about the situation.
Then the epiphany. "Hey, maybe it dropped down into the engine compartment & is resting on top of the bellypan"!
I put the car up on the Race Ramps (garage door down, of course, to prevent any Beatlemania scenes), dropped the bellypan...and there it was.
Bellypan - Yay.