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Originally Posted by Wally
Without a Transmisson/Tractive Effort performance chart, the real engine performance curves, the real transmission losses you are all just guessing.
Truth is, as anyone with a small turbo car can verify, there is a chance this car will be on boost, if not bordering on it, during a freeway cycle, even with front wheel drive. If the engine does end up with direct injection, the issue of running rich to keep the EGTs and det down may be invalid and therefore the economy fairly good.
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A good point Wally. I looked into the issue a bit more (since as i said in my post i dont' claim to be an engine expert) and your post raises a good issue. The problem with the 'on boost' or 'off boost' argument is that is assumes the setup is a very much on or off....fact is that modern turbo cars are not totally light switch (though you can feel it come in pretty easilly).
moreover, the claim that 'on boost' burns copious amounts more than 'off boost' is a bit misguided. Maybe 20 years ago but not now. Withouth performance curves we dont' know for sure, but i think it will do ok on the freeway. Of course, the whole argument is really null and void as anyone knows the I6 is better suited for high load/highway work...the I4T is going to be aimed at fleets with urban cycles....