American made cars in the 60's and 70's were for the most part junk, the final straw was the gas crisis of 72. Most cars of the period rusted out within 7 to 10 years, were unreliable, and the major reason so many people traded vehicles every few years.
In 72 when the gas crisis hit, and gas prices started to rise, people started to buy the more fuel efficient Japanese cars. What they found out was they not only got better gas mileage, but the damn thing ran forever. 100,000 to 200,000 miles on a car were not unusual. American auto companies would spend the next decade or two trying to play catch up on a market here at home that they had just took for granted.