I've tried searching the archives, but I'm never quite sure of my search techniques. Nonetheless, my question is - does anyone know why the 6-cylinder engine was dropped from the S80? I see now only the turbo 5 is offered.

It makes sense about the transmission choice.
However, I have the S80 T6 and the S60 2.4T. With 5 cylinders and a single turbo, my wife beats me every single time with my 6 cylinder twin turbo.
I cannot win.
I have no idea why but the 5 cylinder has more ponies at the wheels.

That's an interesting point. It wasn't that long ago that there was the six and a turbo six. Then the turbo five came along and now both the sixes are gone. Very strange. Volvo must think the five is a better engine. They must also think they can't sell cars in the $40k+ price range. The higher priced S80s always seemed to have rebates of about $8,000 or so. But it's an interesting question - was there something wrong with the six?

It's the transmission. The only transmission that would fit alongside the inline 6's was the General Motors unit, which was a source of high warranty and repair costs, and offered 1 too few forward gears for best fuel economy. The shorter 5 cylinder engine allows the more reliable Aisin-Warner transmission to fit.

The inline 6 was dropped because the transmission was GM..when Ford took over VOLVO the CEO of Ford told Volvo that the GM tranny must go...got this info from a volvo mgr..

The transmission quality story sounds more plausible to me. No doubt being a GM transmission represented a mark against it but automobile manufacturers buy parts from competitors all the time. If it was so clear cut why would it take them seven model years to get rid of it? S80 came out the same year, 1999, as acquisition, and six cylinder continued through 2005. I suspect the real issue was that it was GM and it was troubled.

OK, that makes sense, but what a shame - everything I read about the twin-turbo six gave it high marks for delivering lots of power with minimal fuss.

I see the 6 is gone from the XC90, as well, leaving just the LP turbo 5 in the base model, or the rice-burner V8 for ten grand more.