Jeep Grand Cherokee SRT8 returns to the fold for the 2012 model year packing a new engine, improved ride quality and towing capabilities. A 6.4-liter Hemi V8 sets up shop under the sculpted hood with dual vents to produce 470 hp and 465 lb-ft of torque for an improvement of 50 hp and 45 lb-ft of torque over the previous 6.1-liter mill. Efficiency is also up thanks to an active valve exhaust system, which allows the big Hemi to operate in four-cylinder mode across a wider rpm range. The result, according to Jeep, is a 13-percent increase of fuel economy on the highway and a range of up to 450 miles on one tank of fuel.