A very quick entry, where contributor ‘Nicolas’ can recall seeing a C64 conversion of this early Cobrasoft game, which did see release on the Amstrad CPC: https://cpcrulez.fr/GamesTest/meurtre_a_grande_vitesse.htm
Nothing of the C64 edition can be found online, and with Nicolas being a close friend of a coder in the Babygang group – its possible that a pre-release version of the game was perhaps obtained back in the late 80’s and Nicolas saw that.
Looking on Gamebase, there is a similarly titled game which may be by the very same author of this title called Murder on the Atlantic – its likely part of the same series, as this too was by Cobrasoft: http://www.gb64.com/game.php?id=14700&d=18
Cobrasoft was founded by Bertrand Brocard, and the French wikipedia page (https://fr.wikipedia.org/wiki/Cobrasoft) on the house does list the game for the C64.
Interestingly in 2013, there was a crack intro release for the game, but no actual game. So what happened? … http://csdb.dk/release/?id=117273
Do you know anything more about the development? Did it exist, or did Nicolas play an Amstrad CPC edition?