sorry, could you please ellaborate on that, its all greek to me

and btw, The two tone interior looks fabulous on the 135.

Yeah, the 135 is probably faster then the 335 since the 135 is fitted with a sports pack (includes a sport suspension) unlike the 335.

The 3er coupe has a better drag. That's the point

Nice test

I'm also wondering how the 335i is faster around a track than a sport spec 135i? the 135i is lighter and with stiffer suspension,right?

Maybe the 335i is one of those "well over 300hp" test car 335i's that the BMW fanboys are always going on about!

Seriously though, dede is right, the drag coefficient will make a significant difference on a high speed track. Look at the acceleration times to the lower speeds, the 135i is faster than the 335i. Acceleration to higher speeds the 335i is faster. The 2 biggest surprises for me are the elasticity of the 135i (60-100km/h), only .1 sec slower than the M3 E92, i.e. probably level with an M3 E90 (my next car, although mine will have DCT). Secondly, the 135i outbraking the M3 from 100km/h, even the 335i outbraked the M3 on cold tyres. What's up with that?

Is the chassis of the 3er better than the 1er?

No idea

The 3er is better in one sense: the tire sizes. Even though the 335i has smaller rear tires, it has fatter front tires relative to the 135i: 225's front & rear vs the 135i's 215/245. The 135i was designed for more understeer. This balance may have helped the 335i to drive harder into corners than the 135i, sustain more speed, and get on the gas earlier coming out without scrubbing the front tires. Notice it gets a higher traction rating than the 135i.
Taller aspect ratios can have a subtle effect in more progressive slip. The 135i's sport suspension is not as aggressive as normal sport suspension; this is to provide for a better ride.

The slalom and "wedeltest" (I'm guessing a lane-change maneuver designed to replicate accident avoidance?) is very strange too. Generally an understeering car can be faster, as oversteery or even neutral-handling cars can get into wilder and wilder pendulum-like motions in the rear. And cars on low-aspect tires should do better. But overall (and against expectation), the 335i fared better than the 135i.

Cw is a measurement of how much the body of the car catches the air. A higher value means the body of the car catches more air and thereby loses power that could have been used to push the car forward.