Lexus 2008 IS250 Owner's Manual page 123

2-1. Driving procedures
Changing shift ranges in S mode
Shift the shift lever to the S position and operate the shift lever or shift
paddle switch.
The initial shift range in S mode is automatically set to 5 or 4 according to
vehicle speed. However, the initial shift range may be set to 3 or 2 if the
AI-SHIFT has operated while the shift lever was in the D position.
( P. 125)
Shift ranges and their functions
n
Shift range
6
5
4
3
2
1
A lower shift range will provide greater engine braking forces than a higher shift
range.
124
Automatically selecting gears between 1 and 6
according to vehicle speed and driving conditions.
Automatically selecting gears between 1 and 5
according to vehicle speed and driving conditions.
Automatically selecting gears between 1 and 4
according to vehicle speed and driving conditions.
Automatically selecting gears between 1 and 3
according to vehicle speed and driving conditions.
Automatically selecting gears between 1 and 2
according to vehicle speed and driving conditions.
Setting the gear at 1.
Upshifting
Downshifting
Function