Sapsan, the fastest trains in Russia, travelling at up to 250 km/h (155 mph) and a total length of 250 metres (820 ft) for each ten-car train, connecting St Petersburg and Moscow in just over 3.5 hours.

Sapsan set records for the fastest train in Russia on 7 May 2009, travelling at 290 km/hour (180 mph), but the High-Speed line was built for speeds up to 330 km/h (205 mph).
The ride is smooth, seats comfortable and spacious. Depending on the class of travel, you may be offered a meal and some drinks. I traveled in first (a personal treat), though on observation seats in business and economy are both of equal quality, and there is a snack bar and catering for purchase on-board.
My 6:45am train from Saint Petersburg arrived in Moscow on time at 10:40am, I barely noticed we were flying on the ground. For such a short journey, save yourself some rubles and don't travel in first, splurge instead on a nice hotel.