Even so, they are welcome changes, and the addition of a diesel engine to the Grand Cherokee is a celebration in and of itself. Sure, Europeans are long accustomed to buying diesel Grand Cherokees, but now stateside buyers can enjoy the improved fuel economy and prodigious low-rpm torque provided by the oil-burning engine.

In addition to the newly available 3-litre EcoDiesel engine, with 240 horsepower, a promethean 420 pound-feet of torque and estimated fuel economy of 30 mpg on the highway, all Grand Cherokees will benefit from a transmission upgrade from five gears to a new 8-speed automatic transmission.

This is the gearbox that Chrysler debuted in the Ram pickup truck for model year 2013. The extra gears help boost fuel economy, particularly on the highway. The EcoDiesel’s driving range is predicted to be a bladder-bursting 730 miles. Jeep president and CEO Mike Manley described this as the range to drive from the auto show in Detroit to New York City, with more than 100 miles to spare.  "This engine is everything our customers have been asking for," he said on Monday, "a fuel-efficient diesel with enough power to pull even bigger boats".

The transmission also contributes to a boost in towing capacity for the Grand Cherokee. The 3.6-litre Pentastar V6 engine is now rated at 25 mpg on the highway with rear-wheel-drive, and has a towing capacity of 6,200 pounds, while the diesel and 5.7-liter V8 (formerly known as the Hemi) can pull 7,400 pounds, about the weight of an adult hippo.

V8 fuel economy, meanwhile, vaults to 15 mpg city and 21 mpg highway. If it actually achieves those numbers it will mark a dramatic advance over the V8 Grand Cherokee of the 1990s, which was lucky to see 15 mpg on the highway with a tailwind.

The Grand Cherokee adds an Eco Mode button. No, it does not gently guide you away from flora and fauna while off-roading. Instead, it increases efficiency on the road by dropping the air suspension down into a low-drag configuration at highway speed. It also engages a more aggressive upshift program and cylinder deactivation schedule.

At the opposite, non-Eco Mode, end of the spectrum, the SRT division rolled out an 8-speed version of the ferocious Grand Cherokee SRT, powered by the 6.4-litre Hemi V8. Now the track-ready Jeep will blitz to 60 mph one second faster than before.

At the entry-level end of Jeep’s model line are the Compass and Patriot, a pair of compact crossover models derived from the now-discontinued Dodge Caliber.  Their use of a continuously variable transmission has been the primary shortcoming of these vehicles and contributed mightily to their typically poor reviews.

A new 6-speed PowerTech automatic transmission should deliver much-improved driving dynamics and also promises to boost fuel economy to 30 mpg in highway driving.