60mph...70mph...80mph...

While the government hints that they are considering raising the motorway speed limit to 80mph, this has prompted predictable warnings from safety organisations. But at the same time they have been welcomed by organisations representing drivers.

Who is right? And what would such a change mean for Britain’s fleet drivers?

When fleet managers were surveyed by pollsters a few years ago, they said a rise in the limit to 80mph would be beneficial for their businesses. But is that still correct?

The obvious advantage for professional drivers is the ability to reduce journey times by travelling faster. For example, a 200-mile journey takes 2hrs 51mins at 70mph, at 80mph it would take 2hrs 30mins: a saving of 21 minutes.

Over 20,000 motorway miles, a possible annual motorway total for a busy working driver, that means saving around 35 hours or almost a week’s work.

That saving has to be balanced against increased fuel costs. These are different across vehicles but all will demonstrate a marked jump in consumption from 70mph to 80mph.

It’s not a simple proportionate rise; your engine is most fuel efficient at 56mph. Above that, consumption rises sharply. Government figures suggest the change from 70mph to 80mph could cause a 25% increase. Other more favourable studies have still shown increases in consumption above 10%. Would the reduction in journey time be worth that hike in costs?

In the wider world, the increased speed will be linked to greater environmental damage from emissions and noise, and potentially higher accident and casualty rates. The Transport Research Laboratory warns that the rise could cause 18 lost lives, 64 serious injuries and 363 slight injuries a year.

Research shows that most drivers drive above 70mph on motorways already and that a fifth drive above 80mph. So what would change? Would we all start cruising at 85 to 95mph instead?

The complex interplay of all these factors is likely to mean that any change will only follow a pilot study. The government are looking at the possibility of using one of the new ‘smart motorways’ with adaptable speed limits and lane usage for an 80mph trial run.

And there is one final argument to consider. The Dutch government raised speed limits to 80mph with great popular support. It was real vote-winner. But the cost of changing all the signs and additional safety features was 150m Euros, while drivers noticed hardly any real change from the speed they were driving before. Within six months the vast majority of Dutch drivers thought the speed change was a waste of money.

It’s apparent that there are many factors that need to be considered before the decision is finalised on whether to increase the motorway speed limit to 80mph – what would you decide?

* This is an American website, but includes a fascinating free calculator to compare your journey times and fuel costs at different speeds.

* Read more arguments about the speed limit change here.