Adware has been around for ages and it wasn't always malicious, and Ford Simulator 2 is one of the most intriguing and classic examples of games made simply to advertise. It may not be Forza 3 but it's worth a look. Check out the CGA game FordSim2 in this review of:

Ford Simulator v2 for MSDOS

Made using DosBox, unfortunately. Couldn't get the video out on my old machine to input to my capture device. So goes technology.