New government-mandated MPG standards mean that every automaker is looking for ways to squeeze more MPG out of their cars -- even big, opulent luxo-yachts like the Jaguar XJ. How does the big XJ work with a small engine? Read on.
Jaguar is the latest manufacturer to jump on the supercharging/turbocharging bandwagon as a way to cut the fuel consumption of their cars. For those who aren't familiar with the principle, here's a quick overview: A supercharger is a pump that forces more air into the engine than it would normally "inhale" on its own. (Technically, any method of forced induction, including a well-placed air scoop, is a form of supercharging; colloquially, superchargers are mechanically driven by the engine, while turbochargers are driven by the exhaust.) With more air, the fuel system can supply more gas, which means a bigger bang and more power -- essentially making a small engine produce the power of a big engine.
How does this save fuel? When the supercharger is doing its thing, it doesn't -- all that big-engine power comes with big-engine fuel consumption. But when the car is driven gently, the supercharger produces little "boost" and the small engine acts like a small engine, producing less power and consuming less fuel. Essentially, a supercharged V6 acts like a V8 when you demand power, and drinks like a V6 when you don't.
Most manufacturers have gone for turbochargers -- Ford's EcoBoost series and Hyundai's 2.0T being the best-known examples -- but Jaguar (and Audi) have opted for superchargers. Jag has been supercharging the V8s in top-of-the-line XJs for quite some time now, but this is the first time we've seen a supercharger in the low-end car, replacing last year's normally-aspirated V8.
The Jaguar V6 in action
Let's look at the specs: The new engine is a 3.0 liter V6 that produces 340 horsepower and 332 lb-ft of torque, quite a bit less than the 385 hp and 380 lb-ft of torque produced by the V8 it replaces. But in real-world performance, there's really not much difference: According to Jaguar, the XJ 3.0's 0-60 time of 5.7 seconds is only three-tenths of a second slower than the 5-liter engine. But the difference in fuel economy is remarkable: EPA estimates are 18 MPG city/27 MPG highway/21 MPG combined for the V6 compared to 17 MPG city/21 MPG highway/17 MPG combined for the V8. And you will see those numbers in real-world driving: Despite a test week that was long on city driving and short on freeway time, I averaged 20.9 MPG. Are you willing to give up three-tenths of a second for 4 MPG? I sure am.
Unfortunately, Jaguar hasn't yet entrusted the V6 to the long-wheelbase XJ -- that car still comes exclusively with the V8, despite a weight difference of less than 40 lbs. Not that the short-wheelbase XJ isn't comfy enough, but I do love the stretch-out room in the bigger car. (Not that I get to enjoy it while I'm driving.) And for those who want power, power, power, Jag still offers 470 and 510 horsepower supercharged V8s in the Supercharged and Supersport models respectively.
There's more to the XJ than the engine...
So what of the rest of the XJ? When it comes to luxury cars, this is still one of my favorites: Nothing can quite compare to the wood-and-leather opulence and elegant design of the XJ's cabin. I am finally coming to grips with the rotary-knob shifter; of the four or five test drives I've done, this is the first time I didn't accidentally spin the knob to Park when I wanted Drive. But I can't make excuses for the XJ's electronics; the touch-screen navigation system's graphics look a bit dated, and the refresh rate on the LCD gauge panel is too slow -- the lack of smoothness in the motion of the virtual gauges spoils the effect. (Kia does a better job in the Sorento and Cadenza.) That said, I can't fault the way the XJ drives: The ride is a little firmer than I like in my luxury cars, but the handling is quite good (despite overly light steering) and the smaller engine has no problem keeping up on demanding roads.
Not that any of this matters, because the market has all but ignored the XJ. Big luxury cars are not exactly selling strongly at the moment, and Jaguar sales are a tiny fraction of Mercedes' and BMW's. It doesn't help that the XJ can't be had with the same gizmos as high-end German cars, things like night vision cameras or doors that pull themselves closed. Sure, these gizmos are more useful for showing off than they are in day-to-day driving, but isn't showing off part of the reason people buy big, opulent luxury cars?
There are compelling arguments in favor of buying the Jaguar XJ: Limited sales make it more exclusive, and it's also a bargain. The XJ sells for thousands less than a comparably-equipped Mercedes S-Class or BMW 7-series, and the new fuel-efficient engine is yet another strong argument in its favor.
Would I buy one? Probably not. If I was looking to save fuel, I'd turn to the diesel-powered Mercedes S350 Bluetec, which is good for 25 MPG. If I was looking for a bargain on a high-end luxo-yacht, my pick would be the Audi A8. It's also aggressively priced, and while it may not be as beautiful as the XJ -- what car is? -- it feels like the better-engineered vehicle, with superior electronics, all-wheel-drive, and its own supercharged 3-liter V6. That said, I'm sure I'd feel a faint pang of regret every time an XJ 3.0 drove by. -- Aaron Gold
What I liked about the Jaguar XJ 3.0:
- Big and opulent
- V6 delivers strong acceleration and commendable fuel economy
- More exclusive than BMW and Mercedes
What I didn't like about the Jaguar XJ 3.0:
- Electronics feel a bit dated
- Lacks high-end, high-tech features found on competing vehicles
Jaguar XJ 3.0 details and specs:
- New economy version of Jaguar's flagship
- Price range: $74,075 - $94,600
- Powertrain: 3.0 liter supercharged V6/340 hp, 8-speed automatic, rear- or all-wheel-drive
- EPA fuel economy estimates: 18 MPG city/27 MPG highway (rear-wheel-drive), 16 MPG city/24 MPG highway (all-wheel-drive)
- Where built: Great Britain
- Best rivals: Mercedes-Benz S350 Bluetec, Lexus LS 600h, Audi A8 3.0