He said it started with two or three cars, "which we could handle" but it had got worse, with the cars being moved into position before 8am.
Another shopkeeper said "the main gripe" was Auto Imports and Wholesale were "conducting business on council land, rent-free".
"That's exactly what they're doing. If anyone else did it they would need a hawker's licence."
Many of the vehicles parked along the road are unwarranted and without number plates.
"That's against the law," the shopkeeper said.
A Colourplus staff member said he had "grumped at [the dealership] so much" they no longer parked the cars out the front of Colourplus.
"If they park here they get short shrift from us."
There is a 30-minute parking limit outside Colourplus.
"But it's taken me years to train them not to park in it."
He said the cars were parked along Queen St between 8am and about 5.30pm.
"Normally there is not a spare car park. From 4pm onwards they lock them up for the night in their shed, then the next day they go back out again," he said.
"They shouldn't be on the road -- they're not rego'd or warranted -- and this has been going on for years."
UCOL Wairarapa campus manager Angela Hewitt said it was fortunate there were student carparks on campus, as the Queen St parks were often occupied with the imported cars.
"It means our students can't park there but I understand there is nothing illegal going on so there is nothing we can do."
Ms Hewitt said she was unaware that some of the imported vehicles lacked road-worthy documentation.
Acting Traffic Sergeant Shayne Nolan said police were aware of the situation, but "there are a number of issues to consider with it".
Mr Nolan said it was an offence to have an unregistered, unwarranted car parked on a public street, with each offence incurring a $200 fine.
He would not confirm whether or not Auto Imports and Wholesale had been fined for any offences.
Mr Nolan said the police were working with Masterton District Council to come up with "an agreeable solution".
MDC spokesman Sam Rossiter-Stead confirmed the issue had "been going on for a while" and the council was seeking a solution.
Lawson Hoggard is the director of Auto Imports and Wholesale.
When the Times-Age phoned Mr Hoggard to enquire about the matter he said he would not comment.
"I have a business to run and people to see," he said, before hanging up on the reporter.