Examples of racing series that don't sell as much as they used to?

[Jay520]

The only one I can think of is Need for Speed.

• NFS Underground 2:  9.8m        (2004)
• NFS Most Wanted:     9.61m     (2005)
• NFS Underground :    9.3m        (2003)
• NFS Pro Street:           7.83m      (2007)
• NFS Carbon:                 5.81m      (2006)
• NFS Undercover:         5.16m     (2008)
• NFS Shift:                       3.74m     (2009)

Probably would have sold more if they weren't released every year. Anyone have any more examples of racing series that don't sale as much as they used to. I ask this because many people have stated that racing games don't sell as much as they used to. Games like Mario Kart and Forza continue to sell just as much as earlier iterations. I really want to see if racing games are as popular as they used to.