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[What is GP2Lap] [Download] [Related Utilities] [FAQ] [Future] [Contact] [ChangeLog]

What is GP2Lap

GP2Lap is a real-time GP2 extension made by Frank Ahnert and Ren´┐Ż Smit. It has the potential of adding any number of features to GP2. The current version implements some of them:
  • A logging system. Currently, hotlaps and saved games are being extended with relevant data. This data can also be stored in separate log files.
  • At The Line, showing race times and lap times on-screen as cars are crossing the start/finish line.
  • A track map
  • Car Info. This shows some telemetry data, intended for the external view.
  • Track Manager. Tell GP2Lap which track files it should use.
  • Dual-player mode on ipx networks.
  • Extension of .PAx perf files with car position data and high-res wheel speed. This extended data can be rendered by F1PerfView.
  • Features like custom track menu names and custom split time sections.

Read the GP2Lap Help File file for more info. Also available in other languages (may not be up to date):


Download the latest version from the download page.

Also needed is dos4gw.zip (141KB), which contains dos4gw.exe and you should download it if you don't already have it.

To install, unzip the file to your GP2 directory (where gp2.exe is located). Then read the gp2lap.txt help file for further instructions on how to run GP2Lap.


The GP2Lap source is available on GitHub.

Related Utilities


HOF2Lap is a dos hotlap/game file viewer.

The first versions of HOF2Lap were made by Dave 'Gizmo' Gymer, for use in his HOF2 hotlap league. After Dave abandoned the league he also stopped working on HOF2Lap. Sometime later, when I had added functionality in GP2Lap to attach extended data to hotlaps, I agreed with Dave to take over his project so I could add the functionality of viewing the GP2Lap extended data with it. It's still being used by most GP2 racing leagues to check the validity of participant's submitted files.

HOF2Lap has its own homepage.


F1LapView is a graphical race viewer to compare races logged with GP2Lap. It combines data from each saved game to create a virtual race as if all cars raced at the same time. This is visualized by drawing a trace for each car from start to finish with a height that is relative to the time difference to the leader. There are also virtual traces of the leader for previous laps, so you can see where other cars have been lapped.


WinGP2Lap is a Windows front end for easy editing gp2lap.cfg (screenshot). It was made by Ingo Serf, and can be downloaded from my site. Note that this program needs msvbvm60.dll to work.

Frequently asked questions

For answers on questions that people have asked us regularly, we've put together a small FAQ. Before you contact us with a question, please check if it's already answered in this FAQ first (last updated 19-08-99).

Read the FAQ.

You are also encouraged to use the GP2 forum to ask questions or suggest new features.


People often ask us what the logged checksums mean. Here is the answer:
  • Init checksum: All sorts of grip values, PMI (and lots of other similar values that influence downforce), CC weight, etc. We don't know what a lot of values actually mean, but they might be editable one day so we're logging them.
  • Damage checksum: All the damage limit values that you could edit in GP2Edit.
  • Car checksum: The complete car shape data structure, as it can be edited by the car shape editor. Influence on car behavior still unknown.
  • CC checksum: This one should contain the CC performance values, but for now it's bugged (value often different for different people, sometimes even different for the same person on different days). So please ignore this checksum for now.
  • Track checksum: Same as the last four bytes of the track file. Captures the complete f1ctxx.dat file.

If you are a league director and you want to check these checksums, all you have to do is compare them with a legal saved game/hotlap. If they're different it means at least one of the values that are logged within the checksum is different. For example, if the track checksum is different, it's likely that someone fiddled with the track file (be it intentionally or unintentionally). Remember to ignore the CC checksum, you can't rely on it.

You can see the checksums with HOF2Lap if you use the command line options -d -v with it. If HOF2Lap mentions the word 'incompatible' somewhere in the session output, then the checksums can't be relied upon, because after they were generated, a potentially incompatible game was loaded into memory. If the word 'lap' is mentioned in this same output, it means the session was loaded from a game that already contained lap data (use it to detect reloading).


There are no new features planned for GP2Lap.


Send all GP2Lap related mail to: gp2lap@gmx.net (please include the gp2lap version in the subject). Before you ask a question, please take a look at the FAQ and the GP2 Forum to see if there's already a solution for your problem.


14 Aug 2001 1.15
  • Added a car info page
  • Fixed the country adjectives.
12 Jan 2000 1.14
  • Tyre wear value is now logged. All default values used to be logged within the init checksum, but since GP2Lap now patches this table, it needs to be logged separately, else you'd need to view the hotlap to detect it (car would crash). A note for file checkers: it's best to always view hotlaps anyway, because this is still the best way to check their validity concerning editable values that are not saved into the hotlap file (like the track file).
09 Jan 2000 1.13
  • Built-in track manager. This should fix the problems with distances, average speed, etc. See Track Manager section for more info.
  • Fixed key handler bug. Keys now work in external views again.
24 Dec 1999 1.12
  • Multiple page activation with ctrl key (warning: uses relatively more PO).
  • Screenshots should now work properly with most video cards.
  • If used, HOF2.5 mode is now active for all non-race sessions.
  • Clears 'incompatible' flag after loading a compatible game. If you're viewing old hotlaps, make sure you load a compatible game afterwards to avoid 'incompatibility' problems (or restart gp2 if you want to start a new session for your league).
  • Added paranoia checks for saved game compatibility (loading pre-1.12 saved games will mark them as 'old', and pre-1.07 saved games as 'incompatible').
  • Fixed a problem with loading uncompressed games (normally they were only uncompressed when using the first release of 1.11, which contained a bug that caused this). Thanks to Christopher Brylka and Daniel Ryan for helping out to find this problem. It looks like this caused a large part of all the 'incompatible' games of LFRS drivers.
  • Configurable dot size in track map.
  • Split sector border dots in track map.
  • Change height of page '2' by reselecting it.
10 Nov 1999 1.11
  • Fixed At the Line and added more functionality.
  • Added several .cfg options for At the Line.
  • Rotating track map.
  • VGA support for track map.
  • Added several .cfg options for the track map.
  • Adjustable GP2Lap screen output height.
  • F8 to freeze screen without "paused" message.
  • Rcr values explained by Vincent van Vugt.
  • Pod support. If someone happens to have one, please contact us.
24 Sep 1999 1.10 BETA
  • Removed some more incompatibility problems with Windows. If you had trouble running GP2Lap under Windows before, try this beta version and see if the problem persists. If it does, please contact us again.
  • Fixed GP2 bug that caused it to crash upon saving files under Windows.
  • Fixed saving of races when using a GP2Video patched gp2.exe. Thanks to Rafa for pointing out how to fix this.
  • "Against" in At The Line for comparing sector times and calculating the ideal laptime during non-race sessions. Please note that the 'behind' table doesn't work anymore in this beta. Hopefully this will be fixed in the official release.
  • Added VGA support for At The Line.
  • Creating screenshots with F12 (gp2_xxxx.bmp).
  • Cockpit zooming for more (or less) sense of speed.
14 Aug 1999 1.09
  • Should now run under Windows 98 without 'hanging'.
  • Added an option to hide Windows 3/9x for GP2. This might solve some potential problems.
  • In the track map, computer cars will be gray if they're not in the same lap as the leader.
06 Aug 1999 1.08
  • Added a track map.
28 Jul 1999 1.07
  • Improved checks for changing checksums after loading games. Saved games will now be rendered 'incompatible' not only by loading an extended game with different checksums, but also if the loaded game wasn't extended at all. Also, this flag is kept for much longer (until GP2 quits). The reason is that GP2Lap can't find out what side effects the loading caused. So, if you're participating in a league that uses GP2Lap to validate your saved games, make sure you only load extended games, which were saved with the exact same configuration, or don't load anything at all.
  • Added saving of separate .GLx file with extended information, which also allows logging of computer cars.
  • Disabled CC checksum (as long as it isn't fixed).
02 Apr 1999 1.06
  • Custom split time sections.
  • Custom track names in menu's.
  • Fixed a bug that messed up the custom track name in the extended data.
  • Extra CC performance checksum is being logged.
  • Some extra flags for cheat detection.
  • While (re)loading games the extended data is now preserved.
16 Jan 1999 1.05
  • Bug fix: segment data for track now saved correctly (it gave a load aborted message instead).
10 Jan 1999 1.04
  • Added extension of perf files with car position data.
09 Dec 1998 1.03
  • Fixed pit-in session time and lap time.
  • Added HOF2.5 features. See HOF2.5 home page for more information.
  • Added fast-forward during replays (with f key).
  • Added slomo time to log data (number of seconds the PO was >100%).
  • Some bug fixes.
24 Oct 1998 1.02
  • Added on-screen log output (press 2 during game).
  • Some other minor improvements.
  • Some bug fixes.
14 Oct 1998 1.01
  • Added IPX routines.
  • Added split times during race.
  • Disabled logging of PO before a race has started.
  • Added some experimental stuff (only for experienced users!).
  • Minor bug fixes.
26 Sep 1998 1.00
  • First release.
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