Quebec motorists may have enjoyed a drop in gas prices last year, but they were also subject to a number of "unjustified price hikes" right before the weekend, says CAA-Quebec.

The increases were "excessive and without foundation" for about 65 per cent of the gas price changes made on Fridays in 2015, according to the provincial branch of the non-profit foundation.

CAA called the hikes "unprecedented" and says drivers paid the price when they shouldn't have even as gas prices continue to fall.

"On numerous occasions in Montreal, industry players clearly failed to respect fluctuations in the petroleum price indicators in setting their pump prices," CAA-Quebec said in a news release Monday.

"As a result, motorists were penalized."

Quebecers have still saved hundreds of dollars since 2014 due to a slump in crude prices — though not as much as motorists south of the border.

CAA says there are four main reasons why the cost of refined gasoline has not declined in Quebec at the same rate as that of crude oil:

the higher refining margin.

the coming into effect of the second phase of the Quebec carbon market;

the sharp decline in the value of the Canadian dollar compared to the U.S. currency; and

the tax rate on a litre of gasoline (41 per cent in Montreal).

At the beginning of this week, in the U.S., the average price of a gallon of regular gasoline was $1.749 US, which is equivalent to $0.62 Cdn per litre.

Here's a look at 2015 Quebec gas prices by city:

Average price of a litre of gasoline in Montreal: 116.8

Average price of a litre of gasoline in Quebec City: 109.9

Average price of a litre of gasoline in Sherbrooke: 112.6

Source: CAA-Quebec