We’ve reluctantly returned our iQ to Toyota HQ, and had a chance to reflect on last week’s 500-mile drive.
We set out to prove that iQ is an efficient car, but also that it’s not only possible to match a car’s official fuel consumption figures – you can beat them in real driving on real roads.
iQ’s tank holds seven imperial gallons (32 litres) of fuel; after we filled it to the brim we managed to go for 504.2 miles. Allowing for some extra fuel in the filler pipe, we managed 70-72mpg – the car’s official figure is 65.7mpg.
We’re really happy with our result, but there’s no doubt we could have got further. We drove into the centre of 18 cities and met heavy traffic in several – notably Wolverhampton, Birmingham and Oxford. We had a couple of hours of heavy rain in Wales, and used headlights during six hours of our first day’s driving.
Of course, bad weather and darkness are unavoidable at this time of year (we’re glad we missed this week’s snow), and it’s fair to say that we made a couple of our own problems. Chief among these was our route, which – particularly on the first day’s driving across the West Country – took in many hilly, bendy and narrow back roads. We were surprised to discover just how much more fuel we used on these than on motorways, where we could keep up a more constant, faster speed.
It’s not just our route that would have benefited from a bit of extra research, either. Neither Mark or I had attempted this kind of economy challenge before, and while we sought advice from others who had attempted similar feats, we’ve discovered a wealth of extra resources since we returned – not least of which is the information provided by cleanmpg.com.
What we learned
What we did show is that it’s possible for any driver to save on fuel by changing their driving style. We discovered that doing so takes a bit of practice and a lot of concentration, but that it definitely isn’t dull. It isn’t unsafe, either – many of the most effective techniques rely on good observation and anticipation.
It may sound obvious, but cars use the most fuel when accelerating, so the key to saving it is to accelerate gently and avoid slowing down as much as possible. We learned a lot in our two-day drive – and are by no means experts now – but here are the techniques we found to be easy and effective:
• Don’t drive too quickly – recent tests by What Car? showed that the most economical speed is the slowest that you can drive in top gear without the engine labouring – in iQ’s case that’s about 35mph. But depending on the road, the minimum safe speed may be much higher – we maintained around 55-65mph on motorways.
• Leave a gap – leaving a large gap to the driver in front let us accommodate many of their actions without having to hit the brakes at all. It’s also much safer in an emergency.
• Cornering – throwing a car through corners can be dangerous, but slowing down too much wastes energy. We read the road ahead as much as possible and tried to keep our speed through corners, slowing when necessary by coming off the accelerator well in advance rather than braking. A good gap helps here, as many other drivers slow more than they need to.
• Coasting – on suitable downhill stretches we took the car out of gear and coasted. It’s vital to leave the engine running, though, as it provides braking and steering assistance. Never remove the keys from the ignition when moving.
• Drafting – A lorry or coach moves a huge amount of air, and we picked up the benefits of this by following behind them. Keep a safe distance, though – never get so close you can’t see what the traffic in front is doing, or react in time to an emergency.
You can read comprehensive tips from experienced hypermilers at cleanmpg.com. As we’re happy to admit, we’re novices at this, and we know that our results will be beaten soon.
If you do better, we’d love to hear about it.
Our attempt has attracted criticism in the cleanmpg forums, much of it around our use of ‘hypermiling‘: the term was coined by cleanmpg.com owner Wayne Gerdes. Strictly speaking, having beaten iQ’s combined fuel economy figures we qualify as hypermilers, but Wayne and some of the forum’s members feel that by using the term to describe only a modest improvement over the car’s official figures, we’ve attracted criticism to the concept of hypermiling itself – that certainly isn’t what we intended.