Why is coasting so bad?

Tell me why?

Coasting is when the car is moving but it’s not being driven by the engine – either when the clutch pedal is held down or the gear lever is in neutral. Drivers occasionally coast along the road in when they are not in gear, so in neutral, when they are decelerating, or when going downhill. This saves fuel, and money, however, coasting may not necessarily be safe.

When a car is coasting it is slowing down due to mechanical and aerodynamic grip, and during cornering the mechanical component of this is higher due to the slip angles in the tyres. In essence, it is likely to cause an accident or a skid.

The Highway code states:

This term describes a vehicle travelling in neutral or with the clutch pressed down. Do not coast, whatever the driving conditions. It reduces driver control because:

engine braking is eliminated

vehicle speed downhill will increase quickly

increased use of the footbrake can reduce its effectiveness

steering response will be affected particularly on bends and corners

it may be more difficult to select the appropriate gear when needed

People suggest that it is cheaper to repair brake pads or clutch, however this will cost you on your driving test, and more seriously this could leave you in an accident.

Is coasting breaking the law?

So technically no it's not against the law to coast or to coast downhill. However, if you were to be travelling and coasting downhill you may be deemed to be not in full control of your vehicle and that would be considered as you committing a driving offence.

Why coasting won't reduce your fuel consumption

Cars now a-days are fitted with Electronic Control Units. These help reduce fuel, petrol and diesel usage when the accelerator is not depressed - for example if you are going down hill.

So when coasting downhill, the engine is disconnected from the wheel so, with your feet of the accelerator, the vehicle can't get the rotational propulsion it needs from the wheel. In this case the car starts to idle.

Older cars definitely could save a small amount of fuel but with modern cars with ECU this technique does not work.

So remember: Avoid coasting

If your car is coasting you don't have as much control, and worse doing this while you’re travelling downhill will mean you’ll quickly pick up speed, and you’ll then need to brake harder than should have been necessary.