Enforcement officers have dished out eight verbal warnings to drivers since a ban on idling engines was introduced in Norwich city centre.
But, so far Norwich City Council has yet to issue any £20 penalty notices, as the drivers have obeyed the request to turn off their engines when challenged.
Enforcement officers began taking action in October and revealed eight drivers have been challenged by enforcement officers so far.
In the first instance, the enforcement officer gives a verbal warning and asks the driver to turn off the engine. If the driver fails to comply, then a £20 fixed penalty notice would be issued.
If the driver refuses to provide the necessary details for that fixed penalty notice, then a fine of up to £1,000 can be imposed.
Mike Stonard, Labour's cabinet member for sustainable and inclusive growth, said: 'We publicised the initiative beforehand and we are pleased that the majority of drivers are already switching their engines off when stationary.
'It is clear that a large proportion of the bus and taxi drivers have been briefed by their companies, read the signs or have had some knowledge of the change via published articles, which is very positive.
'So far, no fixed penalty notices have needed to be issued as the drivers complied with the request.'
The ban on idling engines does not apply to vehicles moving slowly due to road works or congestion, vehicles stopped at traffic lights, those which have broken down and those who are defrosting windscreens.
Council leaders insisted the aim of the ban is to change behaviour and cut pollution, rather than rack up fines.
Mr Stonard said it was public transport, rather than general motorists, being targeted.
Streets with particular pollution problems include Castle Meadow, St Augustines Street, Riverside Road, Chapelfield North and St Stephens Street.
An EDP reporter visited Castle Meadow earlier in November to count the number of buses leaving engines on while picking up and dropping off passengers.
In half an hour, of those that waited at least 90 seconds, 11 switched off and another 14 kept their engines running.
One, with a 'not in service' label, kept its engine running for six minutes.
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