1) Tank capacity is not 45 litres... Its 50 litres.
2) If i recall properly, manual book shows its reserve at 6 litres but, based on my experience, its more than that.
3) 36 litres is okay if needle was near the end (E)... I myself have experienced this many times, dont worry.
4) fuel average in cities like lahore is around 9km/litre while on motorway/highway, it gives 13... +/- 0.5km per litre.
14 is possible with light foot but 15 is definitely not! i think any orial prosmatec user should be happy with anything 13+
5) When i had cng, one filled cylinder in lahore used to give me 90-95 km at max. On motorway, it averaged 140-150 while the best i ever got was 173km in one tank (Got it filled from islamabad and travelled on motorway)