We've discussed those posters quite a few times, and every time it has been pointed out that they're an attempt to suggest that the trains are newer than in fact they are. Of course that doesn't mean that with their eventual refurbishment they won't be a consistent improvement.The posters that have been displayed on many stations on EMR local lines say the following:
‘Modern trains, better journeys. We’re rolling out new trains on your route’.
Yes, newer and more modern trains than the 156s that have been running on the routes for the last 15 years, but not new trains, or even new to the routes. They are trains returning to the routes that were used back in Central Trains days. However, I totally agree with @LowLevel that once refurbished they will be a fantastic improvement.
If you have multiple different inconsistent interiors on the same route, but all of which look and feel "modern" then nobody is actually going to notice that other than staff and enthusiasts.