I fail to believe that the BMW 335i sedan can be quicker than the 335i coupe, for a number of reasons.
First, the 335i sedan weighs 3,592 pounds with manual versus the 335i coupe's 3,571 pounds (also with manual). The coupe is lighter by 21 pounds.
Second, the 335i coupe has better weight distribution than the sedan. The 335i sedan's weight distribution with manual is 51.5 front and 48.5 rear. The 335i coupe's weight distributioin is 51.2 front and 48.8 rear (also with manual). The coupe has better weight distribution
Third, BMW lists the official 0-60 time of the coupe as 5.3 seconds with manual and 5.5 seconds with automatic versus 5.4 seconds for the manual and 5.6 seconds for the automatic sedan.
Not to mention, the coupe is lower to the ground than the sedan by nearly two inches.
The coupe was an automatic where as the sedan was a manual. If we look at BMW official times, the coupe with automatic is supposed to go 0-60 in 5.5 seconds and the sedan with manual in 5.4 seconds. That is where there is a .1 second favor for the sedan (4.8) versus 4.9 for the coupe.
Now if we look at the official BMW times for a BMW 335i coupe with manual it is listed as 5.3 seconds versus the 5.4 for the manual sedan.
Therefore if two manual 335is were tested on the same day, one a coupe and the other a sedan, the coupe would be faster on average.
I believe Car and Driver has incorrectly performed their test, and if a random test was done the coupe would be faster than the sedan on the average.