turning the car off every time I get to the rank, or keep it ideling so its hot, given that at the moment its baltic outside 

Keep it warm.

If you kept it idling in South Lanarkshire or Glasgow the Taxi police would take your licence from you or give you a 20 quid fine....
Scottish Gov

 

Edited 29 November, 20169 yr by DEL80Y

An idling car is generating soot but not necessarily generating enough heat for a passive regeneration.

 

Turning it off would be the best option in my opinion.

An idling car is generating soot but not necessarily generating enough heat for a passive regeneration.

 

Turning it off would be the best option in my opinion.

I'd be really surprised if a properly running car generated any soot at idle. Most diesels only produce soot under heavy load, especially in factory tune.

My properly running non-DPF BMW 320d when sat in heavy traffic or left idling for a prolonged period of time would always temporarily emit big plumes of soot when accelerating hard straight after.

 

This would suggest to me soot is indeed generated under light and very light loads, such as idling.

More likely the sudden increase in exhaust pressure blew out soot sitting there from previous high load operation.

Perhaps, but the car was regularly worked hard and the only time it would visibly smoke was after stop start traffic or when sat on tick-over for lengthy periods.