My 91 300E has the part #5 and it is attached by the parts #14 and #17 in photo. There are six of each. The #14 is pushed into the subframe, like a clip really. Easy to do. The panel itself is sealed in the front by #23 which is really a rubber molding of sorts. It keeps air from catching the leading edge.

Why would you want this on your car in the first place? Because it does lower noise (originally installed to meet the tough Swiss noise standards) and it does have the benefit of improving airflow through your engine compartment. Some say it helps prevent heat rising and heat collection in the engine compartment by creating an encapsulation that moves the air specifically from the front of the car to exit area below the firewall. Here in N. California, the summers can get into the 100s. The 300E continues to amaze me in how well it handles the heat with the AC on AND how well this car is in terms of reliability- now with 210k miles. It makes me wonder if the lower panel does contribute to this by moving the hot air away from the engine compartment.

Almost every new car and truck now include this or similiar covers-shaving any aero drag yields improvement in MPGs. Yesterday evening I was helping a neighbor with her full-size Chevy pickup, a 2001 model I believe. She was loosing coolant and I looked under the truck in the front to see if there were any leaks. It also had this underside engine cover. I was amazed.

The panel does improve areodynamics of the underside of the car. Air running under the car buffets against tie-rods, cross members, oil pans etc. True that maybe more appreciated on the Autobahn at 100+ MPH speeds than here in the U.S.

Also, depending on where you live and what you drive through, it does keep road crap off components such as the alternator etc.

As a lot of people have reported, it isn't seemingly a critical part but if my car didn't have one, I'd put it on. Often the part #5 can be found at a junk yard for less than $50. The parts #14 and #17 and #23 can be order from a dealer for my guess, less than $30.

Hope this helps, keep us posted.
Haasman

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'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)