Fiat Chrysler received more than just an ugly sweater and socks from one of its 'kids' this holiday season. A lot more. According to automotive pricing and information website TrueCar, December Jeep sales skyrocketed an amazing 42% (89,654 units sold) compared to a year earlier - making this past December the brand's biggest month ever. Included in that percentage are impressive increases of 36% for the Cherokee and 22% for the Grand Cherokee. Overall, these figures helped push Fiat Chrysler to a 13% sales gain for 2015 and the best December in its history. All this despite a nearly 21% decline in the Chrysler division. While incentives have certainly helped create demand for the Jeep line, it is becoming increasingly apparent that lower gas prices and easier access to credit have re-ignited American's love for the SUV. For 2015, the Jeep line sold 865,028 units domestically - its best showing ever and up 25% over 2014 - while globally it sold more than 1.2 million units. The record December also marked the Jeep brand's 27th straight month of year over year sales increases. "FCA US finished 2015 strong with sales up 13 percent and our best December sales since we started business more than 90 years ago," said Reid Bigland, Head of U.S. Sales. "For the second straight year, the company has topped 2 million in U.S. sales. FCA US sales have now grown annually for the past six years." For 2016, Fiat Chrysler projects even loftier numbers for the line as it will mark the Jeep's 75th anniversary with numerous special edition models, events, as well as a sprucing up of the Grand Cherokee. Related Links: