Try this free slot car lap counter and timer

LapTimer 2000 is a small MS Windows program that will count and time laps on any scale slot car track. Laps are timed with 1/1000 of a second accuracy. Lap Timer 2000 includes hardware interfaces for the Joystick Game Pad, Parallel Printer Port, Keyboard and the RS-232 Serial Communications Port. Slot car tracks with up to four lanes can be used with Lap Timer 2000. A single race or practice session can record up to 4096 laps per lane. The current lap time for each lane is displayed using a large 90 point font to facilitate easy viewing from across a room. The current lap time displayed for each lane is updated each time a slot car passes over the lap counter track. The current lap number will also be updated when a slot car passes over the lap counter. Races can be run for a specified length of time or until a preset number of laps have been completed. A race summary file is created when a race is completed. This race summary file can be viewed or printed. The race summary includes the number of laps completed as well as individual lap times for each competitor. Detailed instructions are provided in the Help file to build the necessary lap counter interface cable, or if you would prefer you can simply purchase a ready-made interface cable. Lap Timer 2000 includes a Hot Laps database. This database can be used to store race results and practice session times. The database includes facilities to record modification notes and their effects. Hot Laps data can be sorted by a variety of criteria, making it ideal for tracking modifications and the resulting lap times. Facilities to export race log files in the Full Grid Online Racing Series format are also included. Screen resolutions of 640x480, 800x600, 1024x786, 1152x864 and 1280x1024 are supported.