I have a 2002 9-5 Aero Wagon.  My experience (which some here disagree
with, but I'm not sure they've driven the US version of the Aero) is that
the Aero is a pretty disappointing car.  

The HOT engine can crank out an amazing amount of power.  The trouble is
that it very seldom delivers it when I need or want it.

I've been told by 3 different Saab mechanics that the Aero's turbo is a
very large turbo with a lot of inertia.  Because it is large, it can pump
a lot of air through the engine and deliver a lot of power.  But because
it has a lot of inertia, it takes a very long time for it to spin up to
the point where it gets into that power stage.

In my car, there is a lag of 1.5-2.0 seconds from "hit the gas" to "full
turbo power."  I've driven 2 other Aeros and they were similar.  Doesn't
matter how fast you're going -- you can be cruising at 4000 RPM and hit
the gas, and the power doesn't fully kick in for over 1.5 seconds.  
That's a long time to wait for power if you're trying to pass on the
highway.  It's an eternity when you're trying to dart out of a side road
onto a busy street.

Furthermore (again according to the 3 mechanics), because of emission
controls, the turbo apparently somehow spins down EXTREMELY rapidly when
you let off the gas -- faster than I can shift.  (I don't see how this
high-inertia turbo can spin down that fast, but it does.)  This means
that you face the same turbo lag on EVERY shift.  Because the car does
have some power before it maxes the turbo, and because you accellerate
VERY rapidly once you finally spin up the turbo, and because you have to
go through the same cycle on every gear, you end up spending VERY little
time in the "full power" mode.  You spend a lot more time in the "geeze
when will this tank finally start moving" mode.  It's maddening.

(My car has a 5-speed.  I believe the engine may be better matched with
an automatic transmission, which would allow the engine to keep torquing
more steadily than a manual, but that's a guess.)

You'll also find the Aero has (comparatively) very little power off the
line -- the turbo isn't spun up.  In 3 years of pretty aggressive
driving, I have NEVER ONCE "burned rubber" in my car.  It CAN'T.  There
isn't enough power there, from a standing start, to do it.  There's
barely enough to get the car moving quickly without choking.  Pretty
pathetic for a "sporty" car that was advertised to have a ruler-flat
torque curve all the way down to 1400rpm.  (I test drove a 2003 9-3 once
and ACCIDENTALLY chirped the tires several times.  After driving my Aero
I just wasn't used to that much torque off the line.)

If you spend all your time on a dynamometer -- like the ones they used to
generate those torque curves -- then the Aero's engine is a monster.  The
steady-state power delivery is amazing.  It would be terrific if you
climb a lot of mountain roads.  It's pretty good for highway driving.  
But if you spend a lot of time driving in town, frankly I think it sucks.  

If I'd understood this before I bought the car, I wouldn't have gotten
the Aero.  I would have gotten the regular turbo 9-5 and probably would
have been a lot happier.

Gary