This week on The Best of Car Talk, Mike’s Lincoln turns into a low-rider every time his 350-pound nephew rides in the back seat. Will it be cheaper for Mike to fix his suspension, or get his nephew to join Weight Watchers? Elsewhere, Marsha is worried her husband is too sane to drive her BMW without killing the clutch; Ralph’s Suburban seems to be channeling the vintage TV game show “Beat the Clock”; and Lee’s air conditioner started a thunderstorm in his Civic. All this and more, this week on The Best of Car Talk.