Flip the XPS 13 over and you'll see the entire base is made of a carbon fiber composite (except for a rather stylish metal ID plate that flips open to reveal the Windows product key and Dell service tag number).
If we've learned anything from watching movies like the Fast and the Furious, it's that carbon fiber mods all over your pimped out car make you a bad ass. Listening to our petrolhead friends, carbon fiber is pretty much the pinnacle of man's engineering prowess: it's lighter, it's stronger, it lasts longer, it's the Chuck Norris of man-made polymers. But as great as it may be for your car, will it actually do anything for your notebook?
According to Dell, the carbon fiber composite used on the XPS 13 is cooler and lighter than magnesium alloy. To test this, we took a laser temperature reading of the base of the XPS 13 at its hottest point (just under the vent) after running a movie on it for 5 hours, measuring it at 37 degrees celsius. We then did the same to our 13-inch MacBook Air, which registered 39 degrees celsius. Not a significant (or even noticeable) difference, but the XPS 13 was indeed cooler.
We weighed the XPS 13 at 1.36kg, while our MacBook Air weighs 1.35kg. However, the screen on the XPS 13 is noticeably heavier, so we decided to take the base plates off both machines.
The XPS's carbon fiber base plate weighed 132g, while the magnesium alloy MacBook Air weighed 158g. Not a lot of difference, but again, the XPS 13 is still the winner. We also noted that the XPS 13's base plate dimensions are quite a bit smaller than the MacBook Air's, which could explain the difference in weight.
The carbon fiber composite didn't exactly blow away its competition, but still, it does seem slightly better on paper. In terms of actual user experience, we also noticed that the carbon fiber base had more grip and is less prone to sliding off your lap.