There had been one D daytime train running for a while, but now the G trains are on the schedule, Beijing West to Xian North in less than 6 hours (one of them less than 5 hours). 8 trains per day, leaving from around 07:00 to 17:30. Prices are around RMB 825 first class and 515 second class, so not particularly cheap compared to the overnight sleepers, which are mostly T's but one of my favorite overnights, the Z19, is still running (bit over 11 hours with only one intermediate stop). Soft sleepers are only around RMB 400-ish. Still though, when you figure in the city-airport-city time sequence and hassle, and the air ticket cost, the bullet train option between these two cities looks mighty fine.