[Jeff@TopGearSolutions]

Originally Posted by mundo74

Still doesn't answer the basic question why a 400 hp motor is more fuel efficient than the n54. The turbo motor should raise efficiency as it uses the spent exhaust to make power. But when you look at it simply the 400 hp motor gives better fuel Econ that the 300 hp.

Car and driver did an article disputing the actual gains touted by downsizing and turbocharging.

That being said I love the torque curve of a turbo motor. Maybe we are paying for that early ~ 1300 rpm torque where as you have to get much higher in the rev range of the 400 na engine to get it. Most people dont drive around at that higher rpm.

If you read what was posted its already answered.... If you still dont understand, dont worry about it, just enjoy the car.

Several factors.

Compression, Gearing, No ability to reach boost columns which use 2 to 4x more fuel, weight, coefficient of friction, powerband, torque band.

A mustang engine doesnt make 400 HP cruising on the highway. It makes it near redline at wide open throttle.

People confuse power with gas mileage.

I had a near 400WHP RSX and I avg almost 30 MPG. I wasnt making 400WHP on the highway cruising though. Maybe 40-60.

Its all about the vehicle and its characteristics which lead to gas mileage efficiency. You cant break it down to one thing.

335i is a different breed in itself. It makes GOBS of torque down below, and is easily into fuel boost columns which in turn use plenty of fuel.

A more efficient methodology for gas mileage on this car would be to actually induce some turbo lag, so your only boosting when your really on it, and higher in the RPM range.

The 335i among other reasons sacrifices gas mileage for low end power and response.

Again, comparing from one car to another is pointless, you will have to nit pick every aspect of every car and come up with dozens of reasons one car does one thing and the other does something else.

[TwinTurboXI]

Is it possible that the N/A mode is bad for our engines?

[stealth-twntrbo]

The car does not read. Accurate MPGs in NA mode it reads lower than it actually is because of the revised fuel preasure, if you search around you should find it in another post. But the accurate mpg is not displayed in dash while on NA map

[Jeff@TopGearSolutions]

Originally Posted by TwinTurboXI

Is it possible that the N/A mode is bad for our engines?

No its not possible. You drive out of boost plenty of times (naturally aspirated) normally.

Originally Posted by stealth-twntrbo

The car does not read. Accurate MPGs in NA mode it reads lower than it actually is because of the revised fuel preasure, if you search around you should find it in another post. But the accurate mpg is not displayed in dash while on NA map

Truth.