[M-17]

Don't know much but this is from wikipedia and more can read there if that helps.

[ame="http://en.wikipedia.org/wiki/Electronic_throttle_control"]Electronic throttle control - Wikipedia, the free encyclopedia[/ame]

The benefits of ETC are largely unnoticed by most drivers because the aim is to make the vehicle power-train characteristics seamlessly consistent irrespective of prevailing conditions, such as engine temperature, altitude, accessory loads etc. The ETC is also working 'behind the scenes' to dramatically improve the ease with which the driver can execute gear changes and deal with the dramatic torque changes associated with rapid accelerations and decelerations.
ETC facilitates the integration of features such as cruise control, traction control, stability control, and precrash systems and others that require torque management, since the throttle can be moved irrespective of the position of the driver's accelerator pedal. ETC provides some benefit in areas such as air-fuel ratio control, exhaust emissions and fuel consumption reduction, and also works in concert with other technologies such as gasoline direct injection.

[ame="http://en.wikipedia.org/wiki/Drive_by_wire"]Drive by wire - Wikipedia, the free encyclopedia[/ame]

Advantages

Safety can be improved by providing computer controlled intervention of vehicle controls with systems such as Electronic Stability Control (ESC), adaptive cruise control and Lane Assist Systems.
Ergonomics can be improved by the amount of force and range of movement required by the driver and by greater flexibility in the location of controls. This flexibility also significantly expands the number of options for the vehicle's design.
Parking can be made easier with reduced lock-to-lock steering wheel travel as with BMW's Active Steering System, or semi-automatic which is available in Ford/Lincoln vehicles in the US, some Toyota Prius in Japan, Lexus LS460 models worldwide and newer European Volkswagen models. Although neither of these are strictly Steer-by-Wire (SbW) because they retain mechanical linkages, they show the capabilities that are possible.

Disadvantages

The cost of DbW systems is often greater than conventional systems. The extra costs stem from greater complexity, development costs and the redundant elements needed to make the system safe. Failures in the control system could theoretically cause a runaway vehicle, although this is no different from the throttle return spring snapping on a traditional mechanical throttle vehicle. The vehicle could still be stopped by turning the ignition off if this occurred. Another disadvantage is that manufacturers often reduce throttle sensitivity in the low-mid throttle range to make the car easier or safer to control - or to protect the drivetrain (gearbox, clutch, etc.) from driver abuse. The feeling to the driver is that the throttle feels less responsive. There are aftermarket electronic kits to increase throttle sensitivity, to re-gain a more direct-feeling relationship between pedal position and throttle valve opening.