The Chevy Suburban K2500 and its cousin, the GMC Yukon XL K2500, fared only slightly better than the Bugatti Veyron with a Green Score of 20. These two SUVs average 10 mpg in the city and 15 on the highway. If gas prices reach $4/gallon, it would cost $156 to fill the 39-gallon tank. Drivers who fill up once a week would spend more than $8,000 on fuel in a year. At this price, a Prius would look enticing to even the most die-hard truck lover.