Fuel Economy : how much can Cd influence it?

I don’t need to tell you more, apart from asking the community a bunch of questions:

  1. The upper engine is mounted on the brand new '08 Coupé with a Cd of 0.23: its clearely a race-oriented engine so, does Cd effect this way the Fuel Economy or…
  2. Is the boxer 4 that bad in terms of consuption?
    Is there something that needs to be fixed in the fiture?

Boxer 4s work absolutely terribly with turbos as they currently are in the game, thus getting nonsense low efficiency. The lower car is also much heavier. There might also be more factors, such as wheels, drivetrain or some equipment.

And I’m pretty sure you have some error in the boxer’s figures, as the peak power, peak torque and their revs don’t seem likely to apply to the same engine.

Answering the question in the topic - very.


Yep, I know it’s a really “pushed to the limit” comparison, but I’m really surprised by the fact that, type of cars apart, there’s such a gap between those engine, considering that the upper one in terms of efficiency is noticeably better than the poor boxer which has pretty average turbos and intake settings

Make 3-4 engines, mount them in 2 different body’s (one with low Cd and one with very high Cd)
That makes 6-8 cars. Then compare. Remember, you have to use the SAME ENGINE in both car body’s.

The 60’s muscle car body seems to have extreme Cd, try that one.

Drag coefficient also affects top speed - a car with a slippery body can theoretically go faster than a car with the same engine in a draggier body, all other things being equal. However, for the purposes of this topic, the short answer is: a body with a lower Cd figure does yield better fuel economy than one with a high Cd, again, all other things being equal.