Server update ate my reply, sorry. Here's a summary from the top of my head. It is incoherent, my apologies.
From what I know, mixed messages about the law. A researcher from CRNS has said recently that the law is vague, but DPGN (General Directorate of the National Police) said years earlier that the law makes police more effective. The police has to my knowledge complained about lack of training.
I doubt legislative change will make a difference since police is only one side of the equation; the repeating customers of the police generally do not follow the law at all and also have a mindset of ignoring the police.
The questions which have to be firstly clarified in court/parliament/elsewhere are: 1. should police try to stop cars at all, and, if so, 2. should police allow stopped cars to flee.
I believe the answers are "yes" and "no", because anything else is the same as ignoring reckless driving and basically a decriminalisation of ignoring the police and the law.
As for how to stop a car... There is no good way to do it in an ad hoc traffic check against an uncooperative, fleeing driver. Shooting the driver is the only way, and there is a really narrow window to do this.
Shooting tires won't stop the car, it may make the car harder for the driver to control or accelerate. Depending on the car type (FWD, RWD, 4X4), the car may still be able to accelerate, with possibly less control, thus putting surroundings in more risk.
Nonlethal devices like gas or taser do not work if the driver window is closed, or if the car moves too fast.
Shooting at the engine may not have effect. Also, it can be difficult to hit the engine at all from the position and angle where verbal commands are likely given (front, near driver window). Furthermore, if the car accelerates quickly, there is a danger of hitting the passengers, bystanders or the driver while aiming at the engine.
In a planned traffic stop, one can have spike mats and obstacles etc. which can help stop a car. These are obviously not available if the car stop is done ad hoc by patrolling police, such as two motorcycle police in this case.
All in all, the police officers truly have a shit sandwich on their hands with these kind of cases, even if they follow the law to the letter.
PS. Not sure if you are aware of events in Baltimore in 2015 but it is interesting in this context. After the death of Freddie Gray, police started ignoring criminal activity to avoid going to jail for "wrong arrest". The effects of this behaviour could be seen on the crime level of Baltimore.