Incentive spending also is on pace to decline on a year-over-year basis for the fifth consecutive month.  November to-date spending is $3,783 per unit, down $285 from the same time last year. Spending on cars is down $784, while spending on trucks/SUVs is down $48.

"Strong transaction prices and lower incentives are helping maintain manufacturer profitability despite the decline in sales," King said.

Thanksgiving weekend is one of the busiest selling periods of the year and is expected to account for nearly 20% of November sales. The long weekend also coincides with the launch of incremental incentives tied to year-end sales events, which present manufacturers with the challenge of maintaining incentive discipline exhibited over the past five months. All indications are that incentive spending will remain below year-ago levels, although in absolute terms, incentives remain high. "With average discounts equal to 9.6% of MSRP in November, consumers still have plenty of opportunity to purchase a new vehicle at a significant discount," King said.

• The average new-vehicle retail transaction price to date in November is on pace to reach $33,697, an all-time record. The previous high for the month of November—$32,609—was set last year.

• Average incentive spending per unit to date in November is $3,783 down from $4,068 during the same period last year.

• Consumers are on pace to spend $36.9 billion on new vehicles in November, down $220 million from last year's level.

• Truck/SUVs account for 71.2% of new-vehicle retail sales through Nov. 18—the highest level ever for the industry—marking the second consecutive month above 70%.

• Days to turn, the average number of days a new vehicle sits on a dealer lot before being sold to a retail customer, is 70 days through Nov. 11, down 4 days from last year.

• Fleet sales are expected to total 263,300 units in November, up 3.5% from November 2017. Fleet volume is expected to account for 19% of total light-vehicle sales, up from 18% last year.

Jeff Schuster, President, Americas Operations and Global Vehicle Forecasts at LMC Automotive, said, "Volume for the year is holding consistent with 2017 but, as the industry plans for a prolonged and significant investment period in future mobility without a return, cutbacks are being made that could affect near-term planning and future programs. Next year will bring a new challenge for the industry and some familiar ones like trade and rising interest rates."

LMC's forecast for 2018 total light-vehicle sales remains at 17.2 million units, but has slipped to just 22,000 units higher than 2017. The retail light-vehicle forecast remains at 13.8 million units, a decline of 1.0% from 2017. Fleet volume remains the growth engine with volume expected to be 5% higher and representing 20% of total light-vehicle sales. For 2019, the forecast for total light-vehicles is at 17.0 million units and retail light-vehicle sales is at 13.7 million units, each declining 1.3% from 2018.