higher compression ratio engines seem to have good power and be more efficient, but if the high octane fuel is not around then it decrease performance as well as performance to overcome this they general tune the maps or deign the engine to bring down temperatures in the combustion chamber to prevent the air fuel mixture from igniting early.
I don't know the engine design on our verna since the vtvt is only made for india cvvt is made for some other countries while most have gdi for which you can easily get design details.
honda fills in 5w30 for their civics and accords and has that as option for the city. Though their service costs is high. Maruti fills 5w30 for the ritz and sx4. ford fills 10w30 or 5w30 for the petrol cars. Audi bmw volkswagen merc skoda also use 5w30 while 5w40 is used for diesels. Tata and fiat uses 5w40 for both petrol and diesel. And only hyundai is stuck using "15w40 for their petrol as well as diesel" That to api-sl for the petrol when the current one is api-sn which is made for fuel efficiencies and to protect the emission control system.
In the name of fuel economy hyundai has put lots of cheap quality thin plastic parts, if they'd replace it with good quality i wonder the fe then. They go by what they say customer has to adhere to, like when i enquired of the oils and they said only what service centre gives you is allowed nothing from the market not even another 15w40 and neither synth.
Only thing is you guys don't have the oil as what was my state and your guys cars are used in the city which makes the oil go thicker fast while mine no.
Karlover do a research on hyundai cars and their fe find out the claimed fe and find out the real life. Do the same for other car brands.
Based on my research there is a very huge variance between the style used to drive some cars preferred the sprinted way while others the sane way. My car definitely wants to be driven in a sort of spirited way if i change gears above 2500 i get good fe if i change gears as how many say to the rpms stick at 1500 and below 1500 its just boring and you need to down shift agree on my take bazooka?
by the way a hyundai service centre told a member gears1313 that crdi city fe 10 is max.
do give a check on this thread as well karlover http://www.theautomotiveindia.com/fo...i-verna-9.html