It's called an air dam, and for the first generation Volt there are two versions of it, the second one being about an inch shorter than the first (thus giving an extra inch of clearance.)
Mine scraped every day for years, but really didn't seem much worse for wear - it's more rubber than plastic (but actually a mix of the two I believe.)
Mine scraped every day for years, but really didn't seem much worse for wear - it's more rubber than plastic (but actually a mix of the two I believe.)