So if the Tundra averages 15mpg overall and my diesel Ram averages 20mpg overall, the Tunda cost 33% more to drive (if your gasoline is priced the same as diesel which it never is). To travel 100,000 miles in the Tundra would burn 6666.66 gallons of gas, the Ram 5000 gallons of diesel. Gasoline and diesel prices vary wildly in the US but if we round both off to $3./gal then the Tundra is gonna cost you $5,000.00 more to fuel than the Ram diesel. Bear in mine I'm using my actual mileage after adding a ton of weight to my Ram...the stock engine averages 27mpg. That's 3703 gallons to travel 100,000 miles. That's a bean counter's perspective...probably doesn't make a bit of difference, people buy what the like. But the long-term costs can and should be a consideration. Somebody is reaching for a calculator in 1, 2, 3.........