1.If you have never visited a car company's website then it's just that Google categorized your profile wrongly and only the car companies are bidding for you when it comes to show an ad.
2. Just a company wrongly retargeting converters (people who have bought a product) with the same product that they have bought.
3. In Real Time Bidding [1] for Facebook, their information about the user is very much lacking [2] so depending on the advertiser that bids you might get very bad ads.
1.If you have never visited a car company's website then it's just that Google categorized your profile wrongly and only the car companies are bidding for you when it comes to show an ad. 2. Just a company wrongly retargeting converters (people who have bought a product) with the same product that they have bought. 3. In Real Time Bidding [1] for Facebook, their information about the user is very much lacking [2] so depending on the advertiser that bids you might get very bad ads.
[1] http://en.wikipedia.org/wiki/Real-time_bidding
[2] https://developers.facebook.com/docs/reference/ads-api/rtb/#...