Some excerpts from the Celerio's Manual (Page5-9)
Do not operate the system as described below. The life cycle of the clutch may be reduced.
1. Using the accelerator pedal to hold the vehicle on an uphill slope with the gearshift lever in the D or M position. If you perform this operation for a certain period of time, a warning buzzer will sound.
2. Holding the vehicle on an uphill slope using the creeping function. If you perform this operation for a certain period of time, a warning buzzer will sound.
Now, how to start on an Uphill, please see below again from Celerio's Manual (Page 5-10):
Starting off on an uphill:
1) Apply the parking brake firmly so that the vehicle does not roll backwards.
2) Shift the gearshift lever to the D position while depressing the brake pedal. Make sure that the gear position indicator in the instrumental cluster displays 1st gear.
3) Release the brake pedal and depress the accelerator pedal gradually, and when the vehicle starts to move, release the parking brake and depress the accelerator pedal to start off.
This is what I'm following in last 6 months of my Celerio AMT ownership and it works butter smooth, whenever required. No roll back, whatsoever.
To add, it's a fun machine with a pepppy engine, always eager. Can maintain speed of 90+ kmph easily. Go for it