Stuff going on in the video:
0:00 Removing the other car
0:20 Repainting
0:30 More repainting
0:45 Removing and simplifying some passenger windows
1:30 Changing nose side geometry
2:00 Changing nose top geometry
2:30 Changing nose front shape
3:00 Removing headcode boxes and buffers
3:25 Changing side and roof cross sections
3:50 Changing rear shape
4:10 Editing windscreens into headlight holes
5:00 Adding headlights/marker lights
5:30 Editing headcode hole into windscreen
6:10 Adding and editing nose colours
6:30 Changing side shape and adding cab window
7:10 Adjusting body height from the wheels
7:15 Replacing wheelsets and bogies
7:50 Adjusting cab positioning
8:00 Removing unnecessary cab elements
8:20 Moving wiper, AWS and engine panel
8:40 Changing interior colour
8:55 Changing bulkhead windows and colour
9:05 Removing unnecessary interior elements
9:15 Adding new seats
9:30 Replacing solid luggage wall with meshed one
9:40 Adjusting final drive gear ratio
9:45 Changing engine torque curve
9:55 Adding turbocharger sound
10:15 Test drive

The built-in modeller is the feature most prominently demonstrated in the video, but the editor will also allow importing 3D-models made in external general-purpose programs like 3DSMax, Blender etc.