Given the high cost of motoring, it is perhaps understandable that some motorists may look to save money by techniques such as coasting, but as we shall see, in modern vehicles - both combustion engine and electric - this isn’t effective, and could be dangerous.
In this article we’ll answer:What does coasting mean and what is coasting in a car?
And does coasting / freewheeling save you fuel?
Read on to find out more…
Coasting definition: What is the definition of coasting?
Coasting - or ‘clutch coasting’ - effectively means moving easily without using power.
Coasting meaning: What is coasting driving?
Coasting is the process of driving a car downhill with either the clutch depressed or the gear stick in neutral - or both at the same time.
Coasting downhill is also sometimes referred to as freewheeling.
What happens when coasting driving?
The effect of clutch coasting when driving is that your wheels are disengaged from the engine, meaning engine braking (using gears to slow down) is not possible.
Coasting means the car is taken down an incline by gravity and the vehicle's momentum.
Why do drivers coast?
Some drivers choose to coast because it disengages the engine; the idea is that coasting will reduce fuel consumption - but does driving in neutral save gas?
It is in fact incorrect that driving neutral (coasting) will save fuel and is actually a bad driving technique to adopt.
Why is coasting a bad idea?
Why is coasting a bad driving technique?
There are a number of reasons why coasting is bad, whether that be coasting downhill, to coast to stop or coasting in any other circumstance:
- You pick up speed quicker and go faster than you otherwise would.
- You have less control because you can’t control speed via engine braking - since the engine is not connected to the wheels.
- It becomes more challenging to take a safe, steady line around a corner - meaning you'll have less control if you cross the path of another road user or other hazard.
- If you do need to re-engage the gears in order to react to a hazard, you'll have less time to do so than if you weren’t coasting.
Is coasting bad for your car?
Coasting driving can accelerate the wear of your car; as you are going faster, you have to use your mechanical brakes more aggressively, which can wear out brakes more quickly.
Is coasting against the law?
While it is not technically illegal to coast downhill, if you get into an accident and you are deemed not to be fully in control of your vehicle, you would have committed an offence.
Coasting during a driving test
As has been established, coasting is a bad habit to get into, and reduces the driver’s level of vehicle control.
If you coast during a driving test, the examiner may deem you to have lost control of the vehicle - which would be an automatic fail.
However, any issues with coasting should be picked up and addressed by your instructor during driving lessons.
Can you coast in an electric car?
While it may be possible to coast in an electric car (travelling in neutral) for a significant distance, the implications may differ depending on the EV model in question. It may be dangerous, too - for example if you nudge the gear from neutral into reverse by accident while coasting (although modern EVs are likely to ignore this).
Additionally, there may be implications as regards maintaining full control of the vehicle. Highway Code 122 warns against coasting (see below).
Coasting isn't fuel efficient in modern cars
Does coasting save fuel? It’s a common question, although perhaps not as common as it once was due to improvements in automotive technology. Coasting - i.e. disengaging the engine from the wheels - isn’t fuel efficient in modern cars because the engine is still ‘idling’ during this process. Indeed, you are better off staying in gear in order to save fuel. Coasting as a fuel-saving technique was possible in older cars, but newer models with their ECUs nullify this benefit. For the vast majority of car owners, the answer to the question ‘Does coasting save fuel?’ is a clear ‘No’.
Why coasting doesn’t cut your fuel consumption
Modern cars are fitted with Electronic Control Units (ECUs). With the engine engaged, these devices reduce fuel use when the accelerator is not depressed - e.g. when you are going downhill.
But what if you are coasting in neutral, going down a hill?
Generally, coasting isn’t a driving technique that EV manufacturers promote when selling their vehicles. However, some marques do harness coasting - such as the Porsche Taycan, which “defaults to coasting instead of aggressive regeneration”. In this case, “the vehicle continues to roll forward, unpowered, using no electricity, and simply harnessing the momentum of the vehicle”
Why is travelling in neutral bad?
Travelling in neutral disconnects the engine from the wheels which, with your foot off the accelerator, means the car cannot get the rotational power it needs from the wheel. In this case, it uses a small amount of fuel to keep engine powered - essentially "idling" - rather than drawing the necessary power from the wheels.
What about older cars: Is coasting a bad driving technique in older cars?
While with older cars and classic cars coasting could save a small amount of fuel, with modern ECUs this technique does not work.
But whether you have an older or a newer car, coasting is potentially dangerous and should be avoided.
What the Highway Code says about coasting when driving:
Further reading on the dangers of coasting is available in the Highway Code (Rule 122):