SI-DRIVE changes a vehicle’s personality – from fuel-efficient cruiser to high-performance muscle car.
As a student studying the internal-combustion engine, Toshio Masuda foresaw a time when engines would be able to change characteristics without replacing systems within them. Later, as Project General Manager of Legacy and Outback for Subaru, he found support for his ideas, and the end result is SI-DRIVE -- an engine control that electronically alters how an engine operates.
The multifunction display
window in the instrument panel
shows the selected SI-DRIVE
Today, SI-DRIVE is found in 2008 Subaru Legacy and Outback models with turbocharged and six-cylinder engines. This feature allows the driver to manage the vehicle’s electronic engine and automatic-transmission controls by switching between three modes.
SI-DRIVE’s purpose is to maximize engine performance, control, and efficiency. As conceived by Mr. Masuda, SI-DRIVE has the effect of giving a vehicle three different engines in one.
Three Engines in One
The modes are selected by a knob located behind the shifter, and they’re marked [I] Intelligent, [S] Sport, and [S#] Sport Sharp. (A Sport Sharp button is added to the steering wheel for 2008.) The selected mode is shown in the multifunction display window in the instrument panel along with a representation of the corresponding torque curve.
Choosing a mode sends signals to the vehicle’s body control module. From there, wiring carries signals almost instantaneously to the engine’s and automatic transmission’s electronic control units. The SI-DRIVE settings change the control units’ programming (mapping).
Programming changes modify engine torque characteristics by adjusting how engine and transmission components function. These components include the electronic throttle, fuel delivery system, ignition, turbocharger wastegate, and automatic transmission response.
SI-DRIVE modes deliver three distinct types of driving.
Intelligent: With its moderate power delivery and smooth drivability, this mode is ideal for around-town driving and for difficult driving conditions such as slick roads or loose surfaces. It is the most fuel-efficient of the three modes.
Sport: This mode is versatile, providing linear acceleration that is as ideal for freeways and suburban streets as it is for climbing mountain roads.
Sport Sharp: Delivering maximum driving enjoyment, this mode is ideal for tackling twisting roads and for confidently merging or overtaking other vehicles on the highway.