The true inspiration behind it came from Google Earth.

Is Shift [Driver 5’s mechanic whereby players can instantly jump from car to car] a means to an end; a way to eliminate on-foot sections without restricting the player to a single vehicle?
In a sense, yes, but it wasn’t conceived as a direct replacement. The true inspiration behind it came from Google Earth. We wondered what it would be like if you could play a kind of ‘Google Earth Live’, with all the traffic driving around the city in real-time and you could grab any car you wanted at any time…we weren’t sure how it was going to turn out, but once we got it working we quickly realised that the mechanic, being so instantaneous, opens up a world of possibilities that just weren’t there before.

Interview of Martin Edmondson in Edge.