6.7km/L must be base on daily Cheras peak hours road.
Everybody try to cut cost, even for luxury car, notice it getting harder to find V8, V10 or V12 car nowsdays.
Mfg can't cahrge u too much for small V6 so might as well just give u Inline 4 instead, just like medium cost house r made of cement bricks instead of clay bricks, developer would only give clay bricks for luxury house, same theory apply, faham ? Sohchai.
You don't take brigs to compare with car engines. No wonder you got everything wrong and failed. My comments are based on automotive engineering results. Mechanical and electrical/electronics work that way and if you do things otherwise, they just won't work.
How many full size and large sedan around? How many could afford them here? Not many could afford to go for 7-series, S-Class, A8, Lexus LS, etc nowadays. V8, V10, V12 are available but these cars would cost over RM800k with road tax ranging from RM8k-24k annually. You didn't use your brain? Even back in 80's and 90's, people mostly go for 1.3L, 1.5L, 1.6L, 1.8L, 2.0L. Bigger than these are less unless you are going for luxury cars.
Cefiro A33 refitted with 2.5L V6 gets 6.7km/L in city driving whereas Camry 2.4L driven the same way and location gets 8km/L. Sonata NF 2.4L even better at 9km/L. Fact is, smaller than 3.0L is not feasible to use V6 engine especially fitted on D-segment. That explains why Teana 2.5 V6 is confirmed fuel guzzling losing to other D-segment 2.4L/2.5L inline4.