Don't believe the spin about speed limiters

Car of the future
The car of the future might not be so much fun to drive

Hot on the heels of Andy Burnham suggesting websites should be censored, we now have a Government quango - the Commission for Integrated Transport - saying that control of your car should be taken away from you. And Christmas isn't even over yet.

This is the proposal: devices for slowing your car to a road's speed limit should "voluntarily" be fitted to as many cars as possible. This could reduce road injuries by "29%".

Should we believe it?

The first red flag is this business about it being "voluntary". If you read the report, you'll see 29% applies only if the speed limiters have no over-ride option and are fitted to 100% of cars.

Let's be honest - more honest than the spin this morning: 100% compliance in anything is only achieved by making it mandatory.

The other pitch being made to Radio 4 this morning, is they would be over-ridable - that is, you could switch them off if you needed to overtake. In that case, the 29% drops to a less impressive 12% fall in injuries - a reduction one suspects could be achievable through other, less intrusive means. Yet even that figure is dependent on universal adoption of speed limiters.

Once again, forget this notion about them being "voluntary".

If we can't believe the spin, can we believe the assumptions behind the ludicrously specific "29%"?

The Motor Industry Research Association told the BBC, "The last thing you need is one car to be overtaking and then pull back in, in front of the cars in front, because that braking event will then cause everybody to start to slow down, which will then compress the traffic, which then causes an incident."

Do the models used to cough up that 29% figure take novel limiter-caused behaviours into account? Or do they extrapolate from historic data only? Unfortunately, we don't know because the models aren't in the report for independent scrutiny.

Finally, there's the politics: do you really want to hand the Government a new tool with which to regulate your behaviour? At the end of the day, if driving is reduced to sitting in uniformly moving queues of metal boxes, isn't that just sitting on a train by another name?