With the LX, Lexus covers the rock bottom of the SUV market, in terms of fuel economy. It's an SUV undercut only by a handful of supercars and ultra-high-performance SUV derivatives.
The LX 570 is rated by the EPA at 12 miles per gallon city, 17 mpg highway. That puts it near the top of the EPA's Carbon Footprint scale, and—based on our assumption that the majority of energy used during a vehicle's service life will be used through the tailpipe—makes it one of the least green choices you could make, of any vehicle sold in the U.S. today.
The Lexus LX 570 is one of the biggest SUVs on the planet--and it's been around in its neanderthal form, as the Toyota Land Cruiser, for a very long time. That doesn't make its coexistence with the Toyota Prius and Lexus CT 200h any easier, though at least Toyota can reasonably argue that it covers every niche in the market.