conan_murder wrote:Stop start system.
Leave this one out of the list please.
As to the matter in hand;
The most efficient way to optimise your current engine would be with changing pistons, but as that is quite a time consuming upgrade you would rather convert your car to 5W30 full-synth oils if it isn't already running on it. While changing between oil types try to find a bigger oilfilter or one with a higher filtration rating.
Adding addictives to your engine oil generally improves it as some oil addictives like Slick 50 for example, it costs a bit but it's quite usefull as it reduces the internal friction of parts and makes your engine go better.
Also adding a little amount of 2-stroke oil into your fuel helps as it relubes the injectors and the fuelpump. while refilling fuel add about a 0,4L 2-stroke oil into the tank.
Drive drive drive until you need to refuel again, you should notice along the way a small kick-in as further friction is reduced from the engine.
Also before adding the oiladditive + changing oil: Drive your car to about 80-90 degrees temp and then drop out the oil. Swap oilfilter! Add only 95% of you oil capacity, the 5% is how much you should add addittives. Then drive carefully (no over revving and stuff) until you can hear that your engine is becoming more responsive (about 200-300Km?)
This treatment should result in a lower fuel consumption-> lower emissions->lower C02 and a better responsive, happier and longer lifespanned engine.
(Warning! If you're unsure about doing it and don't know what you're doing, don't do it. Ask a professional mechanic to perform the oil conversion and also check that your engine is rated to support thinner oils!)