After setting records in 2015 and 2016, car sales slipped 1.8% in 2017, the first decline since the recession. One reason, the huge number of three-year old leased cars that are off-lease. The price gap between those vehicles and new ones: $14,200, up from $10,500 in 2010. 12% more cars will come off-lease in 2018 compared to 2017. Add rising rates, and 2018 car sales will be good; not great.