When the Infiniti G35 was introduced as an early 2003, its 3.5-liter V6 was a major selling point. At the time competitors were selling more expensive cars with smaller engines. Then for the 2008 model year (2009 for the sedan) they enlarged the engine to 3.7 liters, perhaps to stay a step ahead of competitors that had come out with their own 3.5s.

But the market has shifted, and people are seeking fuel economy that the big six cannot provide. So, for 2011 Infiniti will offer a G25 powered by a 218-horsepower 2.5-liter V6, which will be among the smallest sixes offered in the U.S.

I fear that with this engine they have gone too far in the other direction. Since 2006 the competing Lexus IS has been offered with two sixes, one a 2.5 and the other a 3.5. After driving both, I concluded that for most people the 3.0 they have failed to offer in the IS, but have offered in other products, would hit a sweet spot.

The same is likely for the G, as it’s larger and a little heavier than the Lexus. Nissan’s V6 was sweetest in its old 3.0 form. And, in a roughly 3,500-pound car, a 3.0 would get fuel economy at least as good as an overworked 2.5.

For 2011 Infiniti will also launch a new “performance line” by offering the G37 coupe with a 348-horsepower V6. Good to hear–I suggested that this engine would have been welcome in last spring’s Anniversary Edition–but the regular 3.7 already offered far more power than most buyers need.

So how about a G30, Infiniti?