I visited WWW. CARS. COM and saw a car I was interested in. I filled out the left hand side info request which goes to the dealer. Note: this is the only site and only one car I submitted such info.
Of course, I was called by the dealer. But WWW. CARS. COM may have sold my phone number to an automated telemarketing firm which has the number 866-793-0145, which has a lot of complaints on the net. The number has a relationship with auto sales. I haven't answered the phone when the number comes up, but it doesn't stop. If it continues, I will have no choice but to change my phone number.
I read the Privacy Statement for www.cars.com and it says it will use your info and permit affiliates to use it. So if you use the site, do not fill in any info request. Call the dealer directly.