I did this survey last night as well. It was to evaluate the web site of one of the major car rental companies, and it must have been the real site as they warned not to click through to completion or you would have a real reservation. I was expecting to see a 'Finalize' or 'Complete' button before the last page of the survey so I'd know when to stop but I clicked on a 'Continue' button and found myself at a page with a confirmation number! I've booked enough car rentals at web sites to know that I really did have a reservation so I copied down the confirmation number and then went right back in and cancelled it. I didn't put a credit card in, but I did log in since they said to navigate the site as you normally would. Since all my info is stored with them I probably didn't need to put in a credit card #.
I got emails for both my reservation and my cancellation - but again, my email address is stored in my account with them. If you think that you got a confirmation number, I'd contact them to find out. Normally you can look online but only with your last name and a confirmation number. Hope this helps.