Brother if you take care of following things, fuel efficiency might increase:
- Always use recommended engine oil grade. If your car's engine health is perfect, there is no kind of smoke from the exhaust, compression is Great, you are not facing any oil consumption issues, then; 0w-20, (5w-20) 5w-30 and 10w-30 are the recommended engine oil grades for this car. Start from the thinnest, and gradually move towards thick oils, if thins does not suit.
- Whichever engine oil grade you choose, ensure that oil is fully synthetic (its most preferable, but not compulsory), from some reputed brand (like Shell, Total, Caltex / Havoline / Chevron, ZIC, Kixx, PSO, etc.) and 100% genuine and original (most important thing). Oil should meet API SN / SN Plus, preferably with RC (Resource Conserving), and / or ILSAC GF-5 criteria.
- Always use genuine filters; air filter, oil filter, AC / Cabin filter etc.
- Always keep air filter clean. If dirty, clean or replace, if its beyond cleaning.
- Get throttle body serviced (if reqd.) and spark plugs replaced (if reqd.)
- Check the condition and health of hybrid battery packs. Take action as per their condition and requirements. Keep their fan always clean. Clogged fan can result in loss of their efficiency and heat-up issues, thus deteriorating them quickly.
- Always keep wheels balanced and aligned, as / when reqd. / 10-15,000 kms (whichever comes first).
- Always use OEM recommended tyres and rims, and their sizes. Upsizing / downsizing / wider tyres / rims, etc. also effect fuel efficiency.
- Always maintain company recommended tyre pressure.
- Let go of any additional weight in your car (luggage in boot compartment, etc.)
- Although not directly related, but also keep brakes serviced after regular intervals, and fluids also checked, top-upped, replaced (whichever applies at that specific time interval) after their defined intervals.
- Always drive with soft pedal and light foot. Do not accelerate / decelerate abruptly.
These are some of the points coming in my mind right now, by following which might get good fuel efficiency.
I hope, these all help. Thank you.