Just reading the French news this morning, no doubting it was a super professional hit. No bullets hit the body of the car, all cartridges found at the scene match the number of bullet wounds in the three in the car, the cyclist and the seven year old (who was shot in the shoulder).
In a way that is intriguing to the investigation the French are not very welcoming to Arab's (mainly due to Meghrabin influx) but also are historically not very supportive if Israel. I say this because I believe it was a Mossad hit. They have a blasé attitude about how they conduct their affairs, knowing full well the protection they are offered by certain states.
If it was MI-6 they would hardly have waited to come to France to organize a hit. (David Kelly, Dr Holmes etc)
As a human it is act of savagery though, to think that some guy/girl will receive a large bonus payment for wiping out a family and a passer-by is stomach churning.