When we first heard about all of the changes that were coming to the 2014 Jeep Grand Cherokee, it sounded like the company was making a lot of bold statements to grab headlines at the Detroit auto show: New interior! New transmission! Better fuel economy! Better drivability! Better towing capacity! And there's a diesel! As it turns out, the new Jeep lives up to what was promised, and while subtle styling cues are what visually differentiate the new model from the previous ones, the real novelty is discovered by getting behind the wheel and going for a drive.

There aren't many companies out there that offer four engines in their full-size SUVs. The Grand Cherokee line offers a 3.6-liter V-6, 5.7-liter V-8, 6.4-liter V-8 in the SRT, and now, the 3.0-liter EcoDiesel V-6, Jeep offers a broad range of options, one that is comparable to what Mercedes-Benz offers its M-Class customers. All four engines are now backed by the same ZF eight-speed automatic, a significant upgrade from the five- and six-speeds that were offered before. The powertrain changes will please a lot of Grand Cherokee fans and should get new buyers into the showroom as well.

The biggest news for us was that a diesel option was returning to the Grand Cherokee after a six-year hiatus; it should come as no surprise that we spent the most time in a diesel-powered model. Jeep uses a 3.0-liter turbodiesel V-6 sourced from VM Motori, with some changes to make it better suited to the North American market. Jeep added a watercooled turbocharger and increased the rail pressure, plus the engine uses watercooled exhaust-gas recirculation and SCR. Thanks to the EGR and the selective catalyst reduction system, the diesel Grand Cherokee is Tier II, Bin 5, and ULEV II compliant, making it 50-state legal. Like all the other diesels available in full-size SUVs in America, this one uses a urea-based diesel exhaust fluid to ensure that the engine meets emissions standards. Jeep realizes that not everyone wants to refill the 8.5-gallon urea tank themselves, so the company has given it a 10,000-mile service interval, which lines up nicely with the range of a single tank of DEF. For most owners, a trip to the dealer for the regular oil change and service will also include the DEF refill. However, if you do want to do it yourself, its location is right next to the fuel filler behind the fuel door.

The diesel's 240 horsepower is not the story here; the 420 lb-ft of torque at 2000 rpm is. That's 30 lb-ft more than the 5.7-liter V-8, and it's available at a much lower rpm. That torque is noticeable right off the line. Acceleration is excellent with the EcoDiesel, and remains smooth as you get up to freeway speeds. This combination of a torquey engine and terrific eight-speed is tough to beat.

During our drive, we also tried out Sport mode, which allows you to shift via the floor-mounted T-handle shifter or steering-wheel-mounted paddles. The transmission does a fine job of choosing the right gear, but the paddles certainly came in handy off-road. The ride was slightly firm but comfortable, and the cabin was pleasantly quiet. You can hear the diesel a little at idle, but it's not noisy by any means nor is there any noticeable vibration. The diesel engine costs $2300 more than the 5.7-liter, meaning you can get into a diesel Grand Cherokee for $41,290, including destination. The topline Summit we drove was $56,990 as tested--but it was fully loaded. This is the new topline Grand Cherokee trim, sitting above the Laredo, Limited, and Overland. It let us sample the cabin that's the most posh, as well as the best off-road tools the Grand Cherokee has to offer.

If you opt for the two-wheel-drive model, you get the 7400-pound maximum towing capacity and 30 mpg on the highway, providing a range of over 730 miles. Choosing 4WD means a choice of three systems--full-time (Quadra-Trac I, essentially AWD), part-time with a two-speed transfer case (Quadra-Trac II), and Quadra-Drive II, which adds an electronic limited-slip differential--and the crawl ratio can be as good as 44:1. The penalties aren't severe, either: fuel economy goes down to 28 mpg on the highway and towing capacity is a mere 200 pounds lower. Selec-Terrain, the dial-based four-wheel-drive system that lets you choose the right settings based on the type of ground you plan to cover, returns for 2014 with one change: the Sport setting that was there last year is now integrated into the transmission. Now, the choices are Sand, Snow, Auto, Mud, and Rock.

Like Quadra-Drive II and the EcoDiesel, the Quadra-Lift air suspension is only available on Limited and higher models (sorry, Laredo), so when it was time to go off-road, we were happy to four-wheel in a Grand with the ELSD. Jeep had already set up a diesel Grand Cherokee, different from the one we drove on the highway, minus the front airda, which is made to be easy to remove. Taking that piece off greatly improves the vehicle's departure angle. The trails allowed us to see how the Grand Cherokee fared on slickrock, through deep dips, along narrow spots that a full-size truck wouldn't be able to get through without scraping, off-camber, through technical spots, up a highly vertical incline, and down a steep hill. The Grand Cherokee quietly chugged its way through it all, doing things that most luxury SUV buyers will miss out on. It lives up to the Jeep name, and even though the Wrangler is more capable, the Grand Cherokee offers up to 11.3 inches of ground clearance, plus has Selec-Speed Control, which includes both hill-descent and hill-ascent control -- all helpful off-road tools that aren't offered on the Wrangler. The only complaint we had off-road was that in the sun, it's hard to see which orange lights in the off-road cluster near the Selec-Terrain dial are lit unless you use your hand to shade it.

As the top of the line model, the Summit had the highest-level interior, with a new 8.4-inch touch-screen nav system. Like in other new Chrysler products, this is the screen where you control satellite radio and access apps. Here, the passenger tried out the available wi-fi hotspot as we listened to Sirius XM. Another option is Sirius Travel Link, which makes it easier to find diesel stations along the way. The Grand Cherokee now uses LCD gauges that you can set up to show what information you want to see, including off-road data, fuel economy, navigation cues, and more. According to Jeep, it can be configured 100 different ways.

The interior of our on-road tester featured Jeep's Brown-hued leather. Unlike the current standard of using chrome or brushed aluminum trim on the center stack, this vehicle had copper accents. The combination looked elegant and attractive, as the copper was dark, more the color of a tarnished penny than the bright color we usually associate with copper. Other amenities include available USB ports in the front and rear, and rear-seat Blu-ray entertainment. Our tester also had heated and cooled seats and the CommandView two-row sunroof, plus a wide array of safety features. Like the interior, the exterior looks stylish and fitting for a luxury vehicle, with new LED HID headlights and taillights, and a new look for the front fascia, which has a shorter grille. Jeep designers also made a point of giving each trim level cues that differentiate one from another.

After driving on the highway, curving country roads, and on the trail, it was time to switch vehicles and visit the track. In this case, the track was the Circuit of the Americas in Austin, so the most appropriate member of the Grand Cherokee family to go there in was the 2014 SRT ( the "8" has been dropped from the end of the name). Its 6.4-liter V-8 returns with 470 hp and 465 lb-ft of torque. The SRT has a wonderfully mischievous exhaust note and throttle response is very quick. Steering is crisper than in the standard Grand Cherokee, brake pedal feel is firmer, and brake response is quicker. The ride is not as nice as in the regular models and lets in more road abnormalities, but handling is excellent for a performance SUV. SRT pricing starts at $63,990, a comparatively entry price for that amount of performance.

Jeep may have kept the foundations of the Grand Cherokee essentially the same for 2014, but has added a lot of content that increases capability and luxury in an already impressive vehicle. Its base price of $28,690 (with the gas V-6) is only $1100 more than that of the 2013 model. Jeep expects about 15-20 percent of Grand Cherokee sales to be diesel, we think they'll sell more than that. Regular 2014 Grand Cherokees go on sale in March, diesels should be available early in the second quarter of 2013.

2014 Jeep Grand Cherokee 4WD Summit EcoDiesel
Base price $51,990 ($56,990 as tested)
Vehicle layout Front-engine, 4WD, 5-pass, 4-door SUV
Engine 3.0L/240-hp/420-lb-ft turbocharged diesel DOHC 24-valve V-6
Transmission 8-speed automatic
Curb weight 5400 lb (mfr est)
Wheelbase 114.8 in
Length x width x height 189.8 x 76.5 x 69.3 in
EPA city/hwy fuel econ 21/28 mpg (est)
CO2 emissions 0.94 lb/mile (est)
On sale in U.S. May 2013 (est)