When I think of luxury cars, I think of Jaguar first; I can't help it - I'm a fan.The XJ model is the top of the Jaguar sedan line, a large luxury car with lots of amenities, cloud-soft ride and plenty of effortless power.This Jaguar even looks powerful sitting still - streamlined and elegant, yet bold and dramatic. The XJ embodies the soul of a sports coupe in a spacious four-door sedan.Now, for 2013, Jaguar has made a major concession to those of us concerned about fuel economy: there's now a supercharged 3.0-liter V-6 engine available in the XJ, and that's the model I tested. The 3.0 is the new entry-level version of the XJ, with a starting price of $73,200 (plus $875 freight) for the rear-drive model (my tester) and $76,700 for all-wheel drive.It replaces last year's entry model, which came with a 5.0-liter normally aspirated V-8 engine and base price of $73,700.This car is still beautiful and unmistakably Jaguar. It has 340 horsepower, compared to 385 for the lowest-priced V-8 model, the 2013 XJ Portfolio at $81,200. Jaguar says it can go from zero-60 mph in 6.1 seconds, compared to 5.4 seconds for the Portfolio rear-drive V-8, which is not supercharged.An all-wheel-drive version of the Portfolio model, though, comes with the V-6 engine only, and the same zero-60 time as the rear-drive 3.0 model.EPA fuel-economy estimates for the V-6, with its eight-speed automatic transmission, are 18 mpg in the city and 28 on the highway with rear-wheel drive, up from the 15/23mpg for the previous year's V-8.The all-wheel drive is also new for 2013, available only on the XJ and XJL Portfolio, and drops the mileage estimates to 16 city/25 highway.Even with the V-6, my XJ had plenty of power when and where I needed it, and averaged a nice 24.5 mpg during my test, according to the on-board computer.Jaguar has replaced the six-speed automatic with the new eight-speed automatic across the board for 2013, and added an engine stop-start system to every model.These changes are all intended to improve fuel economy without compromising the Jaguar's effortless performance.The XJ is not a hybrid, which is where you would usually find the stop-start technology. It's used to shut off the engine when the vehicle is temporarily stopped - at a traffic light or in heavy traffic - and automatically re-start it when the driver's foot comes off the brake pedal. The first time that happens is a little startling, but I like the idea of not using fuel sitting in rush-hour traffic or in the line at the drive-thru.Standard equipment for the XJ line includes automatic bi-function HID xenon headlights, which provide powerful illumination as light levels fall. The headlight cluster is also attractive, with a strip of bright-white LED Jaguar signature lights along the base. The beautiful headlights also have power washers mounted flush with the body.My XJ came with a Visibility Package for $850, with Adaptive Front Lighting. Its sensors react to the car's speed and steering, directing the headlights around corners as the car turns. Extra LED corner lights illuminate the path beside the vehicle on straight-aways.Intelligent High Beams switch between high- and low-beams to adjust to oncoming or preceding traffic.The taillights are also eye-catching, flowing along the rear fender and sweeping down toward the rear bumper. Some of the 57 individual LEDs are arranged in three blades of light similar to claw marks of a cat - a Jaguar, of course.Chrome side power vents with a sculpted chromed Jaguar badge, according to trim level, add a touch of bling to the front fenders.The signature woven-chrome grille and 19-inch, 10-spoke wheels with all-season tires are subtle and elegant. Wider wheels are fitted in the rear to optimize grip and enhance the sporty, athletic stance.Of course the XJ is very comfortable, with soft-grain leather seats - heated in the front and rear - with at least 12-way power adjustment. Depending on the model, 18-way or 20-way adjustment is also available, as well as front and rear active ventilation.Front-seat adjustments include cushion tilt and four-way lumbar support. A Front Seat Comfort package for $1,400 added massage to the front seats. I enjoyed taking the XJ for a drive just to experience the heat and massage - very nice on a cold day. Front passengers had 41.5 inches of legroom and rear passengers had 39.9 inches.Dual-zone automatic climate control and automatic air recirculation with air particle and odor filtration, humidity control and automatic window demisting made the cabin more comfortable.Front and rear foot-well lights added ambiance as well as convenience, front and rear puddle lamps were a special touch, and an illuminated front storage tray and cupholders were convenient and special.Adding to that, an Illumination Package for $1,700 brought Phosphor Blue accent lighting to the front and rear air vents, the stainless-steel front and rear tread plates, and the trunk-latch finisher. While these were a very special touch, I had a problem with the illuminated vents reflecting in the side glass and outside mirrors unless they were pointed slightly down.The XJ came with a panoramic roof, which extends from the windshield to the front of the rear seat. The glass is dark tinted and reflective to protect passengers from the sun's heat, with power sunshades on each section for extra privacy. The side windows were solar attenuating, hydrophobic, and acoustically laminated glass.Other features such as rain-sensing windshield wipers, heated/power outside mirrors, heated rear window with a timer, three-flash lane change indicators, power-opening/closing trunk lid (using the Smart Key, an inside button or a button on the external trunk lid), garage door/gate opener, auto-dimming rearview mirror, and the JaguarSense glovebox made operation of the XJ pleasant and almost effortless.I especially enjoyed the power trunk lid and rain-sensing wipers.The Smart Key system allows keyless entry and pushbutton start, which is very convenient during cold or wet weather.At start-up, the XJ's virtual instruments come to life. The 12.3-inch LCD instrument cluster looks like analog gauges with high-contrast, sharp-resolution graphics and provides vital information quickly and easily.tuning.Total sticker for my XJ 3.0 was $78,025, including freight and options.That's quite reasonable, considering that for $155,000, you can get the upper level XJL Ultimate with luxurious seating for four, including dual rear iPads with docking stations, a powered passenger table, champagne flutes and a spot to chill your favorite beverage.The automotive columns of Emma Jayne Williams appear weekly in the Star-Telegram. Contact her at email@example.com.