The Riviera DLC class 802/0, numbered as 800002 and carrying First Great Western Green & Gold livery.
I haven't found a way to get this unit moving on Diesel Mode, so I recommend driving it in Electric Mode and using Foobian's God Mode Mod to force current.
FOR TSW 6 OR NEWER
Tags: bi-mode bi-mode-multiple-unit class-800 first-great-western great-western hitachi iet intercity-express-train mainline passenger sea-leopard-reskins tsw-6 tsw6
Required, if you want to use the reskin away from the wires.
TSW 3 Livery Manager (Also works with TSW 6)
For instructions on installing and using the Livery Manager, please go here: https://github.com/RagingLightning/TSW3-LM/wiki/(1)-Getting-Started