ZF 8-speed planetary gear sets


Allpar reader mentalicca discovered that EPA ratings for the Compass, Patriot, and Grand Cherokee SRT8 have been updated. They show that the six-speed automatic added around 1 mpg highway on the Compass and Patriot, over the CVT; and that the eight-speed pushed the Grand Cherokee SRT8 up to 13 city, 19 highway, an increase of 1 mpg in both city and highway mileage.

The CVT was advertised as having superior gas mileage versus conventional automatics, but at the time it was being compared to four-speeds with relatively low ranges; the greater overdrive of the Hyundai six-speed most likely overcame inherent efficiencies of the CVT on the highway, even as it delivered a generally preferred driving experience.  The real surprise of the group was the relatively small gas-mileage boost of the eight-speed automatic when coupled with the 470 horsepower SRT8 engine. Still, at a typical 12,000 miles per year, the transmission swap will save 57 gallons of fuel per year per owner ($205 at $3.60 per gallon), while delivering superior acceleration.
EPA Gas MileageCVT (FWD)Auto (FWD)WA580HP8
Jeep Compass / Patriot FWD21/2721/28
Jeep Patriot / Compass 4WD21/2621/28
Grand Cherokee12/1813/19