The Polish government has reduced the number of vehicles that can qualify for the lower tax rate charged for a commercial vehicle.
In the past, all a car owner had to do to get the tax break was add a metal screen between the passenger seats and cargo area.
"The formula for calculating commercial and passenger cars keeps changing and this tinkering has only brought in instability," said PricewaterhouseCoopers partner David Green in Warsaw. "If this trend continues, only the Smart ForTwo will qualify as a business car under the new law."
Polish industry groups have been pushing for an annual car tax for all car owners that would be based on variables such as engine size and vehicle age.
"We should be trying to stabilize the market," said SAMAR head Wojciech Drzewiecki, "not create barriers."