Speedo accuracy?

Nothing is perfect. That is a point fairly easily ascertained here at CARSguide; no matter how good a car looks, how well it performs, it is never perfect.

But learning last week that car makers are allowed not to be perfect when it comes to the accuracy of a car's speedo, came as a bit of a shock.

Under Australian Design Rules, vehicle speedos are allowed to be up to 4km/h out in their accuracy.

South Australian police are warning that they will soon drop the tolerance level for speeding offences captured by fixed cameras. This is a heavy blow to motorists who largely are doing the right thing and driving at the speed limit, to the best of their ability.

The average driver, unlike a racer, does not have a good concept of how fast they are travelling and relies on the accuracy of their speedo to keep them out of the costly eye of speed cameras.

Now we're being told that speed tolerances could be dropped to as low as 5km/h over the limit, while at the same time our speedos, by law, are allowed to be 4km/h out of whack.

Other contributing factors includes uncertainties such as the angle at which individuals view a speedo needle and throttle control, which can add a couple more kilometres an hour of indiscretion to your speed without you knowing. In short, we'd better all drive at 5km/h under the speed limit to be sure not to be diving into our wallets, or worse, catching a bus to work when we've seen all our driver's licence points evaporate.

For the police to tighten speed tolerances within the region of uncertainty is rude. It also has the potential to be quite unproductive on a road system already choking with congestion. Police say the move is not based on revenue raising, but money-conscious motorists will eventually get the idea and drive slower than what the law states they can.

That means a slower-moving mass of traffic, longer on the road and quite likely, more frustrated drivers who will be willing to take silly risks. It is likely to also lead to a spike in road-rage offences as irate motorists question why the car in front is travelling at only 55km/h rather than the signposted 60km/h speed limit.

Have patience, fellow motorists. Those slower drivers will just be trying to save money as you, too, would hope to do. A couple of hundred dollars for a speeding fine is never a welcome thing.

Tolerance is needed - and if the police won't give it to motorists, we should consider having some for each other when on the road.