fill the CNG in morning before sun gets hot or after sunset, there will be significant difference - we as nation are crooks, the CNG dispensers are tampered & so is there pressure meters.
over a regular CNG day a tank full cost me Rs. 475 for under 7 kgs - & any strike day or routes closure day a tank full cost me Rs. 560 for 7+ kgs I never visit CNG station during sunlight hours though.