I look at it this way... despite having two cars on my insurance. The Nissan was $35k new. Say I get 200,000 miles out of it, that is 17.5 cents per mile. If I spend $6-10k on the car and can get 100,000 miles out of it, that is 6.0 to 10.0 cents per mile. Assuming maintenance costs, tire costs are equal. I've calculated I spend $13.4 cents per mile on gas (Premium at 2.95 for 22 mpg). If I can get 32 miles per gallon on unleaded (2.59) that is $8.1 cents per mile... so now I'm looking at the difference betwen 30.9 cents per mile for my Murano (Gas/Depreciation). With a $6-10k more fuel efficient car i'm looking at 14.1 to 18.1 cents per mile. Assume 4 years and 100,000 commuting miles. That is $14,100 to $18,100 for the fuel efficient car. Figure $30,900 for the Murano. Say I pay $600/year for the additional car insurance ($2400), and I can still save significant dollars. The question becomes "why keep the Murano?" I love the car, and love taking my boat out in the Summer. I'd really like to get 12-15 years out of my Murano. I hope that if I take good care of it, I can make it last awhile. With a commuting car, I doubt I'd put more than 5,000 -10,000 miles a year on the Murano and figure I should be able to easily get 12-15 years out of it at that pace.