Out of Control
Join Date: Jan 2010
Location: Central NJ
Thanked 515 Times in 398 Posts
In the end this is all about a forced compromise. Under light load a 2.0 turbo will consume about the same fuel as a naturally aspirated 2.0 engine, much better than a 3.5-liter V6. Under moderate load it will consume about the same fuel as a 3.5-liter V6. Under heavy load it will consume more fuel than a 3.5-liter V6. Depending on how you drive a 2.0-turbo can deliver much better to slightly worse fuel economy than a 3.5-liter V6. The need for premium fuel would of course change the total fuel cost.
Because of turbo lag, turbos lack crisp throttle response. I find that most noticeable on the highway when attempting to maintain lane position. However after that lag and the turbo is spooled there is much less need to downshift (in a MT) to accelerate. Turbos have very usable low end power.
For me, I typically reserve using my "V6 power" for entering a highway, exiting a tollbooth or passing a car on a two lane road. As long as I can anticipate my need for power by a second or more, a turbo works very well in those circumstances. Turbos are not great for drag racing, but my days of street racing ended 25 years ago. To be candid, with the traction problems inherent to FWD cars, my 6-6 is terrible off the line anyway.
With a MT I definitely prefer a N/A engine to a turbo. With a turbo, you lose boost with each shift and experience a little turbo lag after engaging the next gear. Is that horrible? No. But it is still not desirable. There is an upside however – smoother shifts. Once boost drops there is less torque on the clutch which allows everything to connect easier and more smoothly.
I am a very Jekyll and Hyde driver. I am either very easy on my car or drive it flat-out floored. Not much middle ground. But that driving style in my environment yields an average of 28-29 mpg in my 6-6. I bet with a turbo/6MT combination I could get very similar fuel economy to the current 2.4-6MT, 35+mpg. That improvement in fuel economy should be worth the turbo lag between shifts provided the "highway" pull is the same.
2012 Accord Coupe EX-L w/Nav, V6-6MT
2007 Accord Sedan EX-L w/Nav, V6-6MT (sold)