So far we don't have any mark 3 derived EMUs in the game, and many fit perfectly with some popular in-game routes (photos from the Internet): Brighton Main Line: Class 442 Gatwick Express Class 455 Southern Class 319 Thameslink (not sure if it fits the time period though) Cathcart: Class 318 Scotrail Class 320 Scotrail Some of these could be developed together (318&455) as they share very similar body structures and cabs.
The 455 is a "must" loco dlc in addition for london commuter. Even if im happy with every announcement of a new route, i still hope they do more loco dlcs, especially since the uk has none of them on the roadmap now, except spirit of steam kinda. Threre were many threads about the 442. Looks like its a problem to get accurate traction motor sounds. The others are also nice suggestions. Really hope dtg is considering picking up at least one of them.
There is quite a large family of Mk3 derived units in both AC and DC form. A couple of oddities would be the 2 car Class 456 formerly used on the West Croydon to Wimbledon line (pre Tramlink) and the sole pair of Diesel Electric prototypes of Class 210 which predominantly operated out of Paddington. Many of the features of these units were the same or similar. I too would like to see some arrive in game.
AP has accurate motor sounds for the 442s. However since it's a five-car set substitution would become an issue especially for coupling/decoupling services
A 442 would also come in handy when the inevitable South West main line out of Waterloo arrives, in one form or another. The appeal of the 442 is also that they reused the traction motors off the legendary 4REP units.
455 - Probably better suited to a South London line rather than BML. VIC-LBG it would be ubiquitous though 321/320 - They ran a lot in the North now and of course GEML, so hopefully if they do either of those areas we will see these units Unfortunately not long for the system though as they're being replaced 319 - the cattle trucks of the London Commuter service, and I don't have a place in my heart for them. Would of course be suitable for any "backdated brighton" system, anything on the Thameslink core, South London, MML southern section... And now in the North
Sorry, I meant to say if they make a 321 OR a 320 they should really do both so can be used on all relevant routes (unfortunately DTG seem to make everything very specific to the route they're making, hence ending up with two different 66s and two 377s, but we can but hope)
The Class 318 and 455 would be my preferences- the Class 318 adding a modern timetable to Cathcart and the 455 substituting in for metro services on BML (if we don't get another route featuring them where they could layer back on).