[In all fairness, a little bit of forward planning renders any ice scraper pointless – sitting in the car for five minutes with the engine running will usually clear ice.] Yes but it's also illegal: The Road Traffic (Vehicle Emissions) (Fixed Penalty) (England) Regulations 2002 Road Traffic (Vehicle Emissions) (Fixed Penalty) (Scotland) Regulations 2003

Pay close attention to this person, who it seems refuses to live in the real world. Tell us all...what laws prohibit leaving sausages in the pan, unattended for two minutes, not yet fully cooked?.

Not as black and white as implied. If spoken to stop doing it - simple.

"Vehicle idling is an offence against the Road Traffic (Vehicle Emissions) (Fixed Penalty) (England) Regulations 2002. The law states that is an offence to idle your engine unnecessarily when stationary. If you fail to turn your engine off after being spoken to you may be issued with a fixed penalty notice of £20".