Cars are lasting longer. The expected number of miles travelled over a vehicle's life has risen to 180,000 miles in 2001 from 128,000 in 1977. But, new car buyers tend to keep their cars about the same length of time before trading them in. Using demand and supply analysis show how this change, ceteris paribus, impacts the market for used cars and the market for new cars. (Hint: only one curve shifts in each market).