Motorists have been warned over a driving technique that many wrongly think can cut their vehicle's fuel consumption.
A survey of 1,000 drivers found that 45% admit to driving in neutral - also known as 'coasting'.
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.
However, drivers have been warned that the fuel-saving hack could end up costing them a lot more than they think they're saving on fuel.
Car hire price comparison website LeaseLoco, who conducted the study, has that 'coasting' drivers risk a fine of a £1,000 - and hundreds of pounds in garage bills.
Rule 122 of the Highway Code states that: "Coasting, a term describing a vehicle travelling in neutral or with the clutch pressed down, can reduce driver control."
Failure to have proper control of a vehicle can result in a potential fine of £1,000 or even discretionary disqualification, warns LeaseLoco.
The firm's chief executive John Wilmot said: "Coasting is no longer beneficial to energy efficiency due to the fuel system in the majority of modern cars.”
“When we drive downhill in gear our engine ECU detects that the accelerator isn’t engaged and cuts fuel from going into the fuel injectors. We use no fuel or very little when driving downhill in gear.
"However, when we drive downhill in neutral our engine and wheels become disconnected.
"This forces a small amount of fuel to be sent to the engine due to the car not receiving the rotational power it needs from the wheels, instead of drawing that power directly from the wheels.”
LeaseLoco also said 'coasting' can cause damage to vehicles such as wearing your brakes out and needing to replace your clutch - making it a costly motoring mistake.
