Both the XK and the 6 Series have standard driver and passenger frontal airbags, front side-impact airbags, front seatbelt pretensioners, four-wheel antilock brakes, traction control and electronic stability systems to prevent skidding.
The XKR’s standard 4.2 supercharged V8 produces 30 lbs.-ft. more torque (413 vs. 383) than the M6’s standard 5.0 DOHC V10.
For more instantaneous acceleration and better engine flexibility in any gear, the XK’s engines produce their peak horsepower at lower RPM’s than the 6 Series:
Horsepower |
|
XK8 4.2 DOHC V8 |
6000 RPM |
XKR 4.2 supercharged V8 |
6000 RPM |
650i 4.8 DOHC V8 |
6300 RPM |
M6 5.0 DOHC V10 |
7750 RPM |
On the EPA test cycle the XK8 gets better fuel mileage than the 650i Auto (16 city/25 hwy vs. 15 city/23 hwy).
For better stopping power the XKR Portfolio’s front brake rotors are larger than those on the 6 Series:
XKR Portfolio |
6 Series |
M6 |
|
Front Rotors |
15.75 inches |
13.7 inches |
14.7 inches |
The XK stops shorter than the 6 Series:
XK |
6 Series |
||
80 to 0 MPH |
204 feet |
209 feet |
Road & Track |
70 to 0 MPH |
163 feet |
169 feet |
Car and Driver |
For better traction and acceleration, the XK has larger standard rear tires than the 6 Series (255/45R18 vs. 245/45R18).
The XK’s optional 255/35R20 front and 285/30R20 rear tires provide better handling because they have a lower 35 series front and 30 series rear profile (height to width ratio), which provides a stiffer sidewall than the 6 Series’ optional 40 series front and 35 series rear tires.
For better ride, handling and brake cooling the XK offers optional 20-inch wheels. The 6 Series’ largest wheels are only 19 inches.
The XK has a standard space-saver spare tire so you can replace a flat tire and drive to have the flat repaired or replaced. A spare tire isn’t available on the 6 Series, it requires you to depend on its run-flat tires, which limits mileage and speed before they are repaired. If a run-flat is damaged beyond repair by a road hazard your vehicle will have to be towed. Some models of the 6 Series don’t even offer run-flats.
The XK has a standard continuously variable suspension system. Using sensors on steering angle, speed and other driver inputs, the shocks soften to improve ride, or stiffen when appropriate to aid handling on tricky roads. The 6 Series’ suspension doesn’t offer adjustable shock absorbers.
The XKR Coupe handles at .92 G’s, while the M6 Coupe pulls only .88 G’s of cornering force in a Road & Track skidpad test.
The XK Coupe goes through Road & Track’s slalom 1.7 MPH faster than the 650i Coupe (67.5 vs. 65.8 MPH).
For better maneuverability, the XK’s turning circle is 4.2 feet tighter than the 6 Series’ (33.2 feet vs. 37.4 feet). The XK’s turning circle is 7.8 feet tighter than the 6 Series M6’s (33.2 feet vs. 41 feet).
As tested by Road & Track, the interior of the XK Coupe is quieter than the M6 Coupe:
XK |
6 Series |
|
At idle |
46 dB |
55 dB |
Full-Throttle |
73 dB |
77 dB |
50 MPH Cruising |
66 dB |
71 dB |
70 MPH Cruising |
69 dB |
71 dB |
The XK Coupe has .6 inches more front headroom, 3.1 inches more front legroom, .2 inches more front shoulder room and 2.1 inches more rear shoulder room than the 6 Series Coupe.
The XK Convertible has .5 inches more front headroom, 3.1 inches more front legroom and .1 inches more front shoulder room than the 6 Series Convertible.
Unlike the driver-only memory system in the 6 Series, the XK has standard driver and passenger memory, so that when drivers switch, the memory setting adjusts the driver’s seat, steering wheel position and outside mirror angle and the front passenger seat also adjusts to the new passenger’s preset preferences.
© 1991-2016 Advanta-STAR Automotive Research. All rights reserved.
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