The post calling Need for Speed a Gran Turismo clone was a decent analogy. But then the OP took it literally... even though they're both simulationist racers, they go in very different directions with it. Then again, I don't play either of those games so I could be wrong on my perceptions.
NFS was always a more arcade-style racer, even the most "simulation" of the bunch, SHIFT, was still mostly an arcade racer. Car handling and racing physics aren't "realistic", but fudged to "feel" realistic. It's not as heavy an arcade racer as say, Outrun or Ridge Racer, but more in the middle between "Arcade" and "Sim".
Gran Turismo (and older Forza titles), by contrast, are hardcore simulation racers second only to iRacing on PC. There is wear and tear on the wheels during a race, suspension has a very complex and near-accurate model, wind resistance, drag, etc. It's not "true to life" though, there are a lot of compromises made, even in the newer versions, for the sake of either fun or due to technological limits.
But the simpler way of putting it: in GT/Forza, there is a physics calculation being done with regards to the force/torque applied to the wheels in relation to their individual points of contact with the road, and how that pushes the vehicle forward. In Need for Speed, the car as a whole is a physics object, with various edge-case scenarios and visual trickery to make it *seem* like the wheels are pushing the object forward.
iRacing is an exception here, in that they really went crazy with it: exact mass and dimensions for almost all major internal components, chassis, suspension, driveline, all with complex mathematical simulations to determine the outcome of situations, rather than "if-then" fudging.
Endcap: Need for Speed came out in 1994. Gran Turismo came out in 1997. So NFS wouldn't be a clone of GT anyway
Now saying NFS is a clone of Test Drive, would be more accurate.