When does a hybrid pay off?

The Wall Street Journal compares hybrids to regular cars on a strictly financial basis. They compare the premium you pay for a hybrid against the gas savings the hybrid achieves. Unsurprisingly, the Prius fares best; you'd have the premium recovered after three years of driving 15,000 miles a year using $4 gas. On the other hand, it would take 98 years to get back the premium on a Lexus (which, by the way, is made by Toyota).