Interesting question. I was involved in the repower of several MLW and other locomotives, and all of them had dynamic braking. However, it wasn't regerative braking (like a hybrid); the traction motors produced power under braking then that power went through resistive load banks, and was dispersed as heat. There was no recovery mechanism. I think there may be hybrid locomotives in use, as opposed to manufacturer's demos, but I've never seen one.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue