I figure we could get a 3.2L thread going. I'll kick it off, but hope others can add to it. I've only had my 2011 for a year now, but I've read as much as I could in VIDA and elsewhere. A great debt of thanks goes to Swedespeed forum members who have helped me out over the past year.
If you've ever worked on the twin-turbo T6 engine in the XC90, and wanted something more practical that was easier to work on, the B6324S is the engine for you. It, combined with the 3.0L turbo, comprises Volvo's "Short Inline 6" (SI6) Engines. Supposedly, the block is a smidgen shorter than the 5-cyl. Supposedly. These are designed by Volvo and built by Ford's factory in Whales. It is also used in the Land Rover Freestyle/LR2. Everything on it is easy access, especially under the hood of the XC90. Coming from Volvos older tried and true "Red Blocks", I actually really love this engine. The first iteration of the B6324S had some design issues that were remedied for the 2011 model year's B6324S5 engine. This later version of the engine uses a bit less motor oil, has fewer special tool requirements, and was "optimized" to be a little more efficient.
The normally aspirated 3.2L engine is perfectly "adequate". It's no sports car. I've driven the 3.0L turbo version in an XC60, and that does go like a stabbed rat. That said, the drive train connected to the 3.2L is the same used with the V8 of the same model year, so this engine is well within the drivetrain's limits. I've yet to hear of transmission or bevel gear failures. Yet.
It's worth pointing out that the SI6 engines use a different filter cartridge than the previous generation of engines.
The good (relative to earlier XC90 inline petrol engines):
-"Life time" timing chain
-All the stuff that was difficult to do on the old series of engines (PCV?) is dead simple on the SI6 engines. Some stuff is even easier to do than on my old RWD Volvo's.
-A camshaft driven vacuum pump runs the brake booster instead of an electric pump.
-Oil filter is a cinch to access.
-All of the engine accessories are easy access as they are run off of the Rear Engine Accessory Drive (READ)
150K mile service is a little ouchy: It involves changing the serpentine belt and all that it touches. INA makes a number of the parts, and they can be had relatively inexpensively from FCP Euro. it does require some special tools to remove the decoupler pulley. These tools can be found as generic decoupler pulley tools. I have these written down somewhere. I'm hoping to do a video/write-up on mine in the next few weeks. While at it, do the thermostat housing at the 150K mile service. This service is probably a budget breaker if you do not DIY.
A set of special tools is needed to manipulate the cams and crankshaft should pretty much *any* engine work be needed. This set of tools is available aftermarket on eBay for $250-ish.
The intake manifold is plastic. There are a number of seals both for the manifold-head junction, as well as for the actuators that modulate the runner lengths. The seals for the latter are NLA from Volvo, but can be had from Land Rover. I'll share these numbers ASAP.
Volvo put the two of the four cat converters in the exhaust manifold. Currently, they are wallet cripplingly expensive.
READ units prior to late 2010 model year have failure issues. The system is splash lubricated, and the bearings can be failure areas. Rebuilds are possible, but expensive (A machine ship really needs to do this work), and special tools are needed to get the READ unit out. Used units are available, and have been used, though VIDA claims that each READ unit is machined to be specific to each engine block. The newer "S5" engines (2011-on) have ball bearings instead of needle bearings in the READ unit. This bearing change seems to be a step in the right direction.
The A/C bracket on earlier B6324S engines needed special tools to realign if removed. This, too, was changed for the S5 version, and no special tools are needed.
There's definite hit or miss oil consumption with these engines. I've been fortunate with mine at 150K miles, though people with engines older and newer than mine have reported problems. I'm running 5W-30 Mobil 1.
Please feel free to correct me, and to add to what you know. There are some really excellent folks in this forum that have really helped me.