Kuan,

ESP does something in addition to ABS and steering. It manipulates diagonal pairs of brakes, or single brakes, to keep the car headed in the direction the driver indicates he wants it headed. That kind of manuever is not available with ABS and steering alone.

Also, there are times when ESP comes into play when braking the normal way, with or without ABS, is not part of the series of commands from the driver. ESP, as implemented by MB, uses the ABS sensors, a yaw sensor and a steering angle sensor to determine what the car is doing and what the driver appears to have intended the car do. It then tries to correct, using throttle and braking, the car's course while the driver is still manipulating the steering and likely throttle or brakes.

I have yet to drive a new MB with this system and bring it into play, so I am not able to describe the system in operation from the driver's seat. But I am sure someone else can. I know what it feels like to be under or over steering severely though, with ABS, and think an extra control to dial it out would be welcome. Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)