Income vs car sales in US

In this post, I create an econometric model whose dependent variable is car sales and independent variable is personal income for US over 1976-2020. The series used in this post and their sources as following: Light Weight Vehicle Sales: Autos and Light Trucks: https://fred.stlouisfed.org/series/ALTSALES. Real Disposable Personal Income: https://fred.stlouisfed.org/series/MEPAINUSA672N So, have a quick look at