Introduced in 2007, the current-generation Nissan GT-R is a bit long in the tooth. Rumors about a new-generation model have been flying around for years already, but it seems Nissan isn't yet willing to let the old GT-R go. So why is the Japanese firm still keeping a 13-year-old model in production? Well, Hiroshi Tamura, the GT-R's chief product specialist, explains that the supercar is difficult to redesign and keep it relatively affordable at the same time.