What does this button do?

Among the 2012 Jaguar XJL Portfolio's gadgetry is a checkered flag button that looks somewhat out of place in the extended-wheelbase luxury liner. Checkered flags are synonymous with racing, so the button looks more at home in the high-performance Jaguar XKR and XFR in which it also appears. What's it doing in the plush $80,000 XJL? 

Though it may seem out of place, the XJL's checkered flag button performs a similar function as its higher-performance siblings.

It activates a sporty Dynamic mode that tunes the XJL's engine response, stability system sensitivity and adaptive suspension firmness for higher-performance driving. The XJL's adaptive suspension with adjustable firmness is standard and similar to that of the XKR and XFR.

The extra stiffness provided by Dynamic mode isn't hugely noticeable because the XJ already rides firmly, but our editors noted and welcomed the mode's loosening up of the XJL's stability control system.

Using Dynamic mode, a transmission function is unlocked to give full transmission control to the driver when the transmission's manual mode is activated. In this combination, the car's electronics won't intervene and upshift automatically when the rev limiter is reached. Unless you shift, the engine will bounce off the rev limiter, instead of upshifting like some other cars' performance modes.

Other than dynamic changes, the XJL's gauge cluster — a fully digital display — turns red when Dynamic mode is activated to further state the setting’s performance intentions.