Simplify the following text for a Grade 12 native English-speaking person.
Original: The Class 170 `` Turbostar '' is a British diesel multiple-unit ( DMU ) train built by Bombardier Transportation ( and previously ADtranz ) at its Derby Litchurch Lane Works .
Simplified: The Class 170 `` Turbostar '' is a diesel multiple unit ( DMU ) built by Bombardier Transportation ( previously ADtranz ) at their Derby Litchurch Lane Works , England .