Need for Speed Shift is being developed by the Slightly Mad Studios. On a question from GamerZines, whether SMS had always intended for Shift to be a Need for Speed title, Lead Designer Andy Tutor replied the following:

"Yeah. It (Shift) actually started out as ProStreet 2.

You'll see the obvious references, like we've got the Tokyo track in there, albeit a bit more mature; there's no balloons or anything like that. The thing with ProStreet was that they couldn't go straight from street racing to a track racer - that would have annoyed a few people. So it was really the first stage of the transition, mixing courses with the street stuff, and this is where they (EA) always wanted it to go.

We've had a few battles, you know, 'put cops in, put nitrous on everything', but we just said 'come on, let's do this properly, shall we?' And we did. Shift is the game we always wanted to make, just under a different name to how it started."

NFS ProStreet was the first "outlier" from the Need for Speed series in 2007 and featured more realistic races. It's no surprise the developers took an existing game as a model, but on the technical side it's likely that NFS Shift is based on the Ferrari Project which was put on ice after the announcement of SMS's involvement with the NFS series.

Source: NFS-Planet