Change your filling station to company operated Total. 2ndly, get the engine oil changed to 0W20 from suzuki dealership asap. 3rdly if you get this average in heavy traffic jams, then no other car except hybrid is going to give you this much fuel average.
Lastly, go to some empty road. Toggle the meter to live average and then accelerate the car to some decent speed. Disengage the gear lever and then let the car run free for a while . Instant average should show 40-50kmpl. Remember you must disengage the gear and let the car run freely for this to show. This is just to check if there is any technical fault or not. If the instant average does show the mentioned number (40-50kmpl) while doing this then you should switch your route to a the one with less traffic. If it doesnt then either you didnt do it right or your car has a technical fault. Hope it helps