187.308 led a train of oil tanks westwards towards Süßen on the afternoon of 10 May 2017. The loco was a Bombardier Traxx AC3 electric fitted with a "last mile" diesel engine, owned by Railpool but hired to Lokomotion at the time.
The concept is the same as that used in British Rail's Class 73, introduced in 1962, an electric locomotive with a small diesel engine to enable it to shunt sidings or work on branch lines away from the electrified network. It's just amazing that it took half a century to catch on elsewhere.