I have 97 A 4 2.8 QUATTRO I recentley lost the undercarriage engine shield, and would like to know what its purpose is, and do I need to replace it.....Thanks

 

basically its a sound proofing and weather shield ( also stream lines the air under the car and helps engine cooling ) but many owners cant be bothered putting it back on after an oil change because its a pain, Ive driven for many years without one and no problems ( that's not to say its ok to leave it off if you have it ) if not would you waste the money?