Star Trek Enterprise (2009) engine sound is very much like....

...it sounded very much like the electric drive of daily commuter/subway trains! I have to particularly mention the electric drive of *some* MTR trains in Hong Kong East Rail Line since I live in there atm.

Other models of the MTR trains lalso make a sound very similar when the Enterprise(2009) is about to enter warp, especially when these trains accelerated to a humble 100 kph.

And if it's still not enough, the intro of the film where the USS Kelvin is making a very 'close pass' to the camera. I really thought it's a subway train, not a starship XD. Something about commuter trains, huh??!

At first, I thought the sound was like the Hemi NASCAR engines but it really was much closer to commuter train electric drives