Currently there are 3 TGVs:
Eurostar (is in "the works" i'm getting a bros spriteset, and its bound to be recolored to 2cc)
Currently all 3 run at 300kmh, and introdates are iirc, aprox 1990, 1995 and 2000. Im concidering to "rebrand" the Atlantique to Sud-Est, and dump the topspeed to 240 and the power to its original 6800kw, and ofcourse have introdate 1981.
Eurostar will be a sort of "middle way" with 270kmh topspeed (as it were introduced with?) in 1991, then Thalys in 1995 and duplex in 2000
In the high-speed-train category there is also the Shinkansen 700 (270kmh aprox 1997) and that italian ETR500 aprox 1992/250kmh. Plus also ICE3 in aprox 2000. So there should be an evolution there. As well as the dutch/belgian HST in aprox 2015. I also hope someone will draw the new french TGV/AGV.
There is also a couple of "old" HST's. RAe TeeII (160kmh in 1955ish) and Shinkansen 0 aprox 1965 (210kmh).
Point of all: Have a more evolutionary curve.