What is hypermiling?
With fuel prices at record levels, you might have heard the term 'hypermiling'. Here's how it can help you improve your car's efficiency...
Think of hypermiling as the motoring equivalent of making a tasty meal from yesterday’s leftovers; you can get more miles from each tank of fuel and save yourself a tidy sum, simply by carefully planning journeys and adjusting your driving style.
What’s more, hypermiling isn’t just useful with petrol and diesel models, because many of the same adjustments that work for those will also improve the efficiency of hybrid and electric cars.
In 2021, a team set multiple Guinness World Records by driving a Ford Mustang Mach-E electric SUV from John O’Groats in Scotland to Land’s End in Cornwall – a distance of 840 miles – and stopping just once to recharge.
The version of the Mach-E that they drove was an Extended Range RWD, which covered 302 miles in our summer summer range test – in which we didn’t use any special methods to boost efficiency. So, for the team to have extended that to around 420 miles illustrates just how effective hypermiling can be.
How does hypermiling work?
Hypermiling is broken down into three key parts: planning, preparation and technique.
Planning
Before you set off, think about the route you’re going to take.
Slogging across town through a gridlocked high street isn’t very energy-efficient in a petrol or diesel car, because you’ll be burning fuel to sit still. It’s best to pick a route that’s less likely to be busy, or to travel outside peak hours.
Meanwhile, electric cars thrive around town, where typical stop-start driving allows their regenerative braking systems to harvest lots of energy for the batteries, but they quickly lose range at motorway speeds. This is because the motorway provides fewer opportunities to recuperate energy by slowing down, and because electric cars tend to weigh more than comparable petrol and diesel models. This requires the motors to work harder to maintain the same speeds, using more energy.
Geography plays a role too; if your route is hilly, you’ll expend much more energy – and fuel – going uphill than you would on a flatter road. And while you might save energy by building momentum while going downhill, it won’t fully offset what’s required to go back uphill.
Preparation
You should also check that your tyres are inflated to the manufacturer-recommended pressure. If they’re below that figure, more of the tyre will be in contact with the road than there needs to be. This increases the friction force your engine has to overcome, wasting fuel. But don’t over-inflate your tyres, because this can lead to a dangerous reduction in grip through bends.
Remove any extra weight from your car, too. As mentioned earlier, a heavier car is harder to move, and this means the engine or motor will work harder (and use more energy) doing so.
Finally, remove any unnecessary appendages from your ca, such as roof boxes or flags. These increase the wind resistance your engine has to overcome to move the car, again wasting fuel.
If you’d like to go the extra mile, you can even check your tyres’ energy rating. Each tyre is given a grade based on its fuel efficiency, with the highest being A and the lowest G. Tyres in higher classes have reduced resistance with the road; this diminishes the force a car’s engine or motor has to overcome to move, consequently saving fuel or charge.
According to the European Commission, which assigns these ratings, a class A tyre will waste 9% less fuel than one in class G. Although class A tyres are often more expensive, you might well save money in the long term by choosing one.
Technique
Make sure that you’ve enabled your car’s stop-start mode (if it has one), which automatically turns off the engine when you come to a stop. This will prevent you from wasting fuel going nowhere.
If your car has an automatic gearbox, or if it’s a hybrid or electric model, it’s likely to have an ‘eco’ mode that further boosts efficiency. In traditional petrol or diesel cars, this tends to disengage the engine from the driven wheels under light loads.
That removes the resistance force produced by the gearbox and reduces how much momentum you lose when not accelerating. And by maintaining as much momentum as possible, you reduce how hard you have to work the engine or motor to maintain or regain speed – thus reducing your energy consumption.
In hybrid and electric cars, Eco usually increases the strength of the regenerative braking, harvesting extra energy as the car slows down and sending it back to the battery to help eke out the range.
If you’re driving a plug-in hybrid, you can also use EV mode – or be careful with the accelerator pedal – to use electric power as often as possible at low speeds, where the motors are most effective. This will reduce how often your engine kicks in around town, minimising how much fuel you waste in stop-start traffic.
This mode is best used around town, though, because most hybrids have fairly small batteries that will quickly be depleted on faster roads.
Avoid using electrical appliances such as air conditioning, heating or demisters if possible, because these add to the strain on your engine and increase fuel consumption. If it’s hot, a better solution (at town speeds) is to open a window instead. However, you should use your air-con at least once a week to prevent parts from seizing and leaving you with expensive repair bills.
You should also consider where you park; a shaded spot on a sunny day will help to prevent your car from getting too hot in the first place.
Now that you’re on the move, try to drive as smoothly as possible. Read the road ahead and give yourself plenty of room to react to any hazards so that you can maintain your momentum instead of wasting it by braking and speeding back up again. This is less critical in electric cars, because braking will send some energy back to the batteries.
If you drive a car with a manual gearbox change up early – but not so much that the engine struggles. Diesels tend to be especially punchy at low revs, and this means they’re particularly receptive to this technique.
Also remember that the speed limit is just that – a limit – and not a target to exceed. Maintaining high speeds demands more of your car’s engine or motor, massively increasing energy consumption.
Research by What Car? suggests that driving a diesel car at 80mph saves roughly 10 minutes every 100 miles compared with maintaining 70mph, yet uses up to 25% more fuel. And according to the Energy Saving Trust, the increase in energy consumption caused by high speeds is more significant in electric cars.
What Car? says…
Realistically, you won’t have many opportunities to exploit every facet of hypermiling at once. For example, if you’ve got young children, it’s unlikely that you’ll be leaving the house without their buggies in the boot – even if they do add weight and use more fuel. And if you live in a city, it’s unlikely that there will ever be a time of day that’s completely free of traffic.
Moreover, your travel times will take a slight hit if you stick to slower speeds and avoid rapid acceleration to save fuel.
That said, with fuel and electricity prices as high as ever, integrating a few of these measures into your driving could save you a substantial amount of money in the long term.
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