Guilt-free motoring has become one of the key selling points for luxury car makers, and the 2013 model year Jaguar XJ is the British brand’s efforts to keep up in the efficiency stakes with the Germans.

There are no styling changes to Jaguar’s flagship sedan, which launched in 2010, and instead there’s a major revision to its range of drivetrains – including two new downsized petrol engines.

There’s a new supercharged V6 that will replace the normally aspirated V8 in Australia and some other markets, and a new four-cylinder turbo that’s a variation on the 2.0-litre EcoBoost engine now found locally in the Ford Falcon.

Both are mated to a new ZF eight-speed automatic gearbox that is also applied to every other engine, which includes a pair of supercharged 5.0-litre V8s and a 3.0-litre V6 diesel.

Jaguar Australia says it will monitor media reviews of the 2.0-litre turbo four XJ and assess any subsequent consumer feedback before deciding whether to import what is a remarkably small engine for a limousine segment where customers are accustomed to vast amounts of effortless power. (2013 model XJs could arrive in Australia as early as October.)

If CarAdvice’s view accounts for anything, we’d say import it.

The Jaguar XJ 2.0 I4 Ti is highly impressive, holding its own against the new supercharged V6 (more of which in a moment) that will also power the upcoming Jaguar F-Type two-seater sports car.

There’s a mere 177kW of peak power found at 5500rpm, with 340Nm of torque produced between 2000 and 4000rpm. These are low figures in limo world.

Yet, the XJ four-cylinder moves away from standstill is a sufficiently responsive manner before the engine hits its stride through a lively mid-range, revving smoothly and enthusiastically beyond 6000rpm.

It’s also nicely matched to the new eight-speed auto, with the transmission picking its upshifts and downchanges at appropriate moments.

We recorded average of fuel consumption of 10.0L/100km exactly during a day’s driving on a mixture of roads, with variations of speed, in and around the English Cotswolds during the international media launch.

That’s close to the official figure of 9.3L/100km, which would be good if the supercharged V6 wasn’t just a fraction less efficient at 9.4L/100km.

Blame that on the turbocharged four-cylinder’s omission of a stop-start system that is standard on every other Jaguar XJ engine.

That rules out fuel consumption as a reason to buy the 2.0 I4 over the supercharged 3.0 V6, though if the four-cylinder were to come to Australia it would become the most affordable model. The cheapest Jaguar XJ is currently $165,000 drive-away.

The V6 naturally offers more power and torque – 250kW and 450Nm.

We tested in a slightly heavier, long-wheelbase Jaguar XJ, but still close enough to a direct comparison of the two engines.

And based on drives of the two models, the 3.0-litre V6 is not better than the four-cylinder in every respect.

It has the edge in responsiveness over the four-cylinder above 3000rpm, feeling even more muscular in the mid-range, though it lacks some fizz at lower revs.

The V6’s acceleration is quicker through the mid-range if far from explosive in comparison, and the bigger engine neither felt as consistently smooth in its power delivery nor as refined at higher revs.

Response from the eight-speed auto didn’t always help, either, with a particularly noticeable delay on kickdown.

The Jaguar XJ 3.0 V6 is only two-tenths slower than the non-supercharged V8 that will continue in some countries, such as the US – reaching 100km/h from standstill in 5.9 seconds. The Jaguar XJ 2.0 I4 takes 7.5 seconds.

Even allowing for the weight and dimensional difference between short- and long-wheelbase XJs, the four-cylinder version feels a little lighter on its feet and has a front end keener to turn into corners.

Regardless of which Jaguar XJ model you choose, however, this is the limousine to pick if you’re an executive with a penchant for sporty driving.

The XJ’s agility is notable for such a large car, with Dynamic mode stiffening the variable dampers to bring another level of body control.

The steering delights with its linearity and accuracy even if some extra heft wouldn’t go amiss.

Jaguar, however, has tweaked the suspension for improved compliance. The company says it was a normal update in line with the introduction of new engines rather than response to customer feedback or media criticism of the firm ride.

There seems to be some extra suppleness to the XJ’s suspension, though the big Jag still doesn’t isolate its occupants as well as a Mercedes-Benz S-Class.

The ride just avoids harshness over potholes but small and medium sized bumps are still felt more than is expected of a luxury limousine.

Large 20-inch and 19-inch wheels with relatively low profiles fitted to our 3.0 V6 and 2.0 four-cylinder test cars respectively wouldn’t have helped matters, with the bigger rubber generating more noticeable tyre noise.

Otherwise there are few other changes to report for the Jaguar XJ.

There are no alterations whatsoever to the exterior styling, though the XJ remains thoroughly contemporary and distinctive.

There are a number of updates for the Jaguar XJ’s audio and sat-nav systems – though Jaguar is still playing catch up with other luxury brands in terms of driver assist systems such as night vision, lane departure and lane keeping systems.

And, as a result of a disagreement over increased costs, Jaguar has switched all of its models from Bowers & Wilkins audios to music systems from Meridian.

We’re not audio experts, but our test of the 386-watt Meridian audio suggested the sound quality is a slight step backwards from the brilliant B&W systems.

Regardless, that sound is filtered through multiple speakers into a cabin that is suitably dressed in generous amounts of leather, slabs of wood veneer and, in our LWB Portfolio test car, suede cloth for the headlining.

If the XJ’s cabin doesn’t match the ultimate impeccability of the rival Audi A8, it still carries a sense of British class with a cool, modern edge.

And if you’re a businessman who prefers to be at the business end of a car’s cabin rather than the back seat, the Jaguar XJ is a leader among limos.