Of all Jaguar XFs, the least sensible are the ones with R in their titles and supercharged five-litre V8 engines under their bonnets, namely the bonkers 503bhp XFR and the even more unhinged 542bhp XFR-S. A distant third overall, but easily the leaders in the non-R category, are the supercharged three-litre V6s.There are two of these, one the £48,495 Premium Luxury which sounds like it should be the best-equipped car in the universe but is actually one step below the even more expensive £51,395 Portfolio tested here.You can have both trim levels with other engines, and there's a very good case for pointing you in the direction of those instead. First of all, they're cheaper to buy - no other non-R XF costs more than £50,000.And they're much cheaper to run. Each of them has official combined fuel economy of at least 47mpg, and the highest CO2 rating of the whole bunch is 159g/km. The supercharged V6s come in at 29.4mpg and 224g/km, which means, among other things, that you'll have to pay £105 extra in Vehicle Excise Duty per year at the very least.But all those others XFs have diesel engines, and you might not like those. (The three-litre is pretty good, though. You should try that one. No? Oh, okay.) And it's quite possible that if you have an inclination towards Jaguar and £50,000-plus waiting to be spent you might not be quite so concerned about fuel bills and VED payments as that bloke over there with the Dacia brochure under his arm.In which case, welcome to the supercharged V6 XF. Its 335bhp engine - driving the rear wheels through an eight-speed automatic gearbox about which there is nothing bad to be said - is one we've encountered before in what is so far our favourite F-Type.It goes through fuel at a fair old rate, as previously mentioned, but it can get the car from 0-62mph in under six seconds and always feels as if it has more than enough power for any situation.Pushed hard, it sounds terrific. Under no pressure, it's very quiet. That's a nice combination, and quite appropriate for a Jaguar.The ride quality is excellent. This is not something I've said about any Jaguar for a long time. The company's policy of fitting very large wheels (because customers want them and are willing to pay for them) without adjusting the suspension to suit has had villainous results in recent years, and in my opinion it has led to otherwise fine cars being ruined.It seems that a similar opinion within Jaguar has been allowed to rise to the top. The test car ran on 20" wheels and 35-section tyres, which would normally lead to kidney-pummelling disaster, but the springing and damping are sufficiently soft to curb their effect on the XF's ride.Well, I say "sufficiently" soft. In fact I think the chassis engineers have overdone it, because the body control isn't all it might be, and if you want to tackle corners with any kind of gusto you'll soon find that it's difficult to place the car on exactly the piece of tarmac you intend to. It's not quite, as my music teacher used to say about conducting the school orchestra, like taking a jellyfish for a walk on an elastic lead, but it's heading in that direction, and I think Jaguar could usefully devote some time to making this XF a little sharper than it is at the moment. Engine 2995cc, 6 cylinders Power 335bhp Transmission 7-speed automatic Fuel/CO2 29.4mpg / 224g/km Acceleration 0-62mph: 5.9 seconds Top speed 155mph Price £51,395 Details correct at publication date