i am sure it will take 4L only.
But as passo has separate guage checking for gear oil, so the best way is to pour 3.5L gear oil in the sump and check the level with the guage. if its low, then add bit more and then check again. You can continue till the guage level shows full.
After that Start the car and drive for a minute. then let the car cool down and then check the oil guage again to confirm its level. If it shows full then its fine. Otherwise you can top it up a bit more as required.