When Paul Newman calls and offers you a custom-built Volvo estate with a Ford 302 5-liter V-8 and a Kenne Bell puffer, always accept. Which explains how the retired and newly bearded Late Night host ended up with this accident-prone, 400-horsepower monster/grocery getter. The powertrain isn’t the only Ford swap; it’s also got a Mustang T5 manual tranny. Letterman famously let Jerry Seinfeld punish the tires on Comedians in Cars Getting Coffee.