Just wanted to add my $.02 to this thread. I am actually a Research Director for a marketing research firm. Everyone who has commented on this thread is right in some aspect.
Those who said that reputable research firms do exist such as JD Power, Maritz, RDA, etc. are absolutely correct. These firms are registered with the international councils on Marketing Research such as ESOMAR and CASRO. Therefore, any surveys with these company logos, or the logos of the manufacturer of the vehicle, are always
safe. Please fill them out, including the personal information! They help us shape the vehicles, advertising campaigns and dealer experiences we all recieve every day!
As for some of the myths: OEMs don't just use research they subscribe to, ala JD Powers. In fact, this is the smallest source of research material that OEMs use. Much more information comes from proprietary studies conducted through companies like Maritz and RDA. Sometimes these have the OEM logo, sometimes the research company logo.
As for the personal information, we use that to develop vehicle and market segmentation profiles. As someone else mentioned, we want to know if the average Escape Hybrid driver is a male or female, highschool or college educated, makes 30K or 130K, etc. That way, we know whether to advertise in Field and Stream or GQ, on the Oprah show or Food Network.
As for unscrupulous companies wanted to sell your info - hey, we all know they are out there. However, as mentioned above, there are some good guys. Make sure you don't punish them, your OEM, and ultimately the customers!
Just a bit of learning from someone who does this for a living!
Happy Driving (and survey taking),