Just watched motorweek review of the XJL AWD.

On their acceleration runs they achieved 0-60 in 5.3 seconds, quicker than the 5.0.

Quarter mile was well under 14 seconds at over 100 mph.

On their test of the XF they achieved only 6.1 seconds 0-60 times and that for the rwd model. Their quarter mile was over 14 seconds me under 100 mph.

Same drivetrain and same weight. Same aero. What gives?

I can understand a few tenths between different cars and on different days but 0.8 seconds?

Any ideas? BTW, my AWD XF feels much quicker than my older 4.2 but officially the two cars are with a tenth or two of each other.

 

Well, your new XF makes more hp and torque. It should be quicker.

And, don't believe those guys on Motorweek.
They tested the 5 liter Xj 0-60 in 5.8 seconds. 60-0 breaking 131ft. All of which are false data.

 

My initial thought would have to be tires?
Tires are the one thing that could make that much of a difference.
Top gear got in trouble for this cause they used near racing tires when doing the lap with a pagani recently, or something like that.
Ford was caught doing this too I think?

Does anyone know if they specially use different or more grippy tires?

 

The XJ they tested was on Dunlops. The XF seems to be fitted with Continental as for my car.

But .8 seconds can't be tires.

 

The XJ is made of aluminum while the XF is all steel construction, therefore, heavier by more than 100 lbs. Having said that, my experience with my own XF vs. my XJL is that the XF feels quicker. Perhaps because it is more agile. The larger XJL and the XF are about the same weight.

Albert

 

The curb weights listed are within 50 lbs of each other. The rwd XF is lighter than the XJL.

I checked Jaguar USA website for listed curb weights.

Using aluminum saves only a relatively small amount of weight on a modern car, about 300 lbs in the case of the XJ.

Mind you, imagine what an aluminum XF might do. It might be only slightly heavier than an F Type.


Maybe it's a launch thing.

 

I find that the XF - and I'll extend the comment to the other models as well - require a bit more experimentation than most cars to figure out what the best launch approach is. That, and I think some variability in rubber and how aggressive the tester wants to be would explain a lot of difference. In the CD review of the F-Type V8, they commented about how heavy it is. Seems like all the models are within a couple hundred pounds.

 

The active air springs in the rear of the XJ might make some difference in preventing too much squat, allowing the tires to hook up more quickly and not bog.