The product name for Deutsche Bahn's fast, point-to-point InterCity Express connections. In other words: schedule-wise the f*cking fastest trains in Germany.
A total of ten Sprinter departs daily on the following relations:
Normal ICE 1 (401-series) trains are used; all Sprinter rides take a scheduled time of about or less than 3-1/2 hours. The morning Sprinters leave at about six o'clock to get businesspeople to their appointments before ten.
To ride a Sprinter, other than the usual ICE ticket, a seat must be reserved and an extra fare paid; the cost for the reservation is included in the extra 10 euros (second class) or 15 euros (first class). On-board personnel has airline-like training, is at least bilingual and serves a free snack and (hot or cold) drink to first-class passengers and distributes free newspapers. Second-class passengers are served from a snack caddy. The usual ICE BordRestaurant (dining car) is of course also available.
On leaving a Sprinter, one gets a cutesy giveaway such as chocolates in the shape of the DB logo in a box decorated with ICE photos.
Factoring in the time for two airport transfers and boarding, taking the Sprinter is usually faster than taking an aeroplane. However, it is not expected that DB will extend their Sprinter network anytime soon, as there simply aren't many other relations where non-stop service at a higher cost would pay off well. For a non-ICE "business train", check the Metropolitan.