Despite it now costing less to register a vehicle, parking officers are ticketing an increasing number of vehicles in the city with expired registration and warrants of fitness (Wofs).
Mr Youngson said the number of tickets issued for vehicle safety generally averaged about 1000 per year, except for the 2013-14 year when staff shortages meant fewer patrols and fewer tickets.
However, the number of tickets issued jumped to 2970 in 2014-15 and climbed again by almost 70% in the 2015-16 year.
"It's a bit of a leap, and we don't know why. Maybe it is a sign of the economic times?''
The number of vehicles found without a Wof was actually higher than the official statistics indicated, he said.
That was because fines for having no warrant were waived if the vehicle owner could produce proof they had obtained a warrant within 14 days.
The ICC retains the money from parking and vehicle safety infringements.
Asked if parking wardens were being more vigilant about registrations and warrants to boost the council coffers, Mr Youngson said "definitely not''.
"We have always checked registrations and warrants. This is not a money-making issue, it's a vehicle safety issue.''
Another concerning trend was the increasing number of deregistered vehicles still being driven on Invercargill streets, Mr Youngson said Parking wardens had begun keeping a list and in the past few months it was "approaching 100''.
Parking wardens did not put tickets on those vehicles, he said.
"There is no point, as when they check the registration the information comes up as ‘owner not known'.''
Mr Youngson said he was so concerned about the trends he intended to raise the issue at the next Community Partnership meeting between ICC staff and the police.
Acting Senior Sergeant Deon McNaught, Southland's acting area road policing manager, said police officers routinely inspected warrants and registration labels at roadside checkpoints and had not observed any noticeable increase in the number of vehicles with expired warrants or registration, nor in the number of deregistered vehicles on the road.
An advantage of checkpoints as opposed to ticketing an unoccupied parked motor vehicle was that police officers often spoke to the owner, which provided opportunities to offer roadside safety tips and advice to motorists, and also gave owners the opportunity to explain any reasons why there might be any defects to their vehicle, he said.
The police offered a 14-day compliance scheme for warrants expired for less than 30 days, and fines were cancelled if one was obtained.
"Police treat the safety and standards of all motor vehicles on our roads with a high priority. It's so important that any vehicle being driven - no matter how long or short the journey - is up to the required safety standards to be on the road,'' he said.
