The BR Class 313 is a commuter EMU (Electric Multiple Unit) operated by Southern, and the Class 313-2 operates using a third rail rather than a pantograph. The 313-2's main home is the East Coastway DLC, so you're going to need that to run it. East Coastway runs from Brighton to Seaford & Eastbourne, and the 313 has its own tutorial, some journeys, scenarios and over a hundred timetabled services to complete. If you have it, you'll also get 12 mostly-shortish positioning services for the 313 on London Commuter.
While I think that TSW2 has enough EMUs the 313 is a much-requested, long-awaited addition to the TSW2 fleet. It was extremely popular with drivers and passengers alike (it's a football fan matchday favourite.) This Southern edition looks great with its green & white Southern livery and "landmarks" graphics which feature; Chichester Cathedral. Brighton Pavilion (and yes, like many at first glance I thought it was the Taj Mahal too) and Portsmouth's amazing Spinnaker Tower.
Checking out the 313's past I found that as of January this year (2021), with the retirement of the Class 483, the 313s are the oldest EMUs in regular service on National Rail in Britain, with the oldest units now over 45 years old! - although after the refurbishment which saw them designated as the 313-2 you'd never believe it. Sister units also served on the East London, Merseyside and Strathclyde commuter networks.
I've driven the 313 a lot, a lot more than I needed to for the purposes of this review. The 313 drives beautifully, while it's no racehorse with its 75mph max speed (but as usual with TSW2, you can make it go faster if you really try!), but has powerful, accurate brakes and responsive traction motors, although there may be times when you search for the 313's Nitrous Oxide Boost or Tardis Time Travel levers as some of the timetables seem impossible to stay on schedule with–but that's probably just me.