The 1% Rule: A Quick Way to Judge a Car Lease Deal “What is the 1% rule for quickly evaluating a car lease?” The most accurate way to judge a lease is to examine its key components— price (cap cost), residual value, and money factor . However, you often don’t have that information when you first see a deal or receive a quote from a dealer. When that happens, the 1% Rule offers a fast way to estimate whether a lease payment is reason able. It’s not exact, but it’s a useful ru