Simply put, “truck-based” SUVs are generally perceived to be less economical at the fuel pumps. These days, the worse the vehicle’s efficiency; the more likely it is that sales numbers for that vehicle are dwindling. Phrases like “truck-based” or “body-on-frame” or simply “real SUV” stand in stark contrast to increasingly common terms like “crossover” CUV” or “crossover utes”. 
Does the perception match reality if applied to the smallest examples of tall-bodied, lofty-drive driving position, usually all-wheel drive vehicles? In a word….. yes. While not necessarily the most fuel efficient or least fuel efficient drivetrain combinations for each vehicle are applied here (many transmission choices make little or no difference these days; sometimes the engine doesn’t either), this sampling of vehicles are relatively well known and position themselves as tough or carlike. 
Except for one, that is. Suzuki wants you to think that its Grand Vitara is in between; merging the best of tough with the best of car.  Guess what – the fuel efficiency story agrees with Suzuki, dropping the Grand Vitara in between the tough SUVs and the more car-like CUVs.
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Hummer H3 V8 – 14mpg
Jeep Wrangler 6-spd man – 16mpg 

Toyota FJ Cruiser man -16mpg

Nissan Xterra man – 17mpg

Dodge Nitro 4.0L – 17mpg

Suzuki Grand Vitara man – 18mpg
Ford Escape – 19mpg
Hyundai Santa Fe – 19mpg
Kia Sportage – 19mpg
Toyota RAV4 – 21mpg

Honda CR-V – 22mpg