I found my wife's new S-type quite accommodating. We used to fit her
previous Ford Ka next to my behemoth Mercedes-Benz 560SEC quite easily.
The larger size of the S-type was to a degree offset by the slightly
smaller doors (the Ka being a Coupé, like the 560SEC :-)

I had to park both cars within about 1 inch (2.5 cm) of the garage
walls, so I needed some help.  I fixed wooden battens to the walls above
the "danger points" and nailed old carpet to the wood to hang down below
the danger, so if there was a collision, at least it would be between
car and carpet, not between car and rough concrete blocks.
Then I hung old tennis balls (I admit raiding my border collie dog's
supply) from strings tied around the rafters (or nailed on, in some
cases). I knew when the strings twitched that I was getting close to
colliding with something expensive.

With this setup, I can park both cars inch perfect (a ball to mark the
windscreen/rear window position is also recommended) so that I've never
scraped the walls, and I always have about 14 inches between the cars -
just enough to wriggle out, as long as I don't put on any more weight.

If I do put on more weight, I suspect I'll have to trade the 560SEC for
a Ka - my wife would never part with her beloved S-type.

Thanks Steve and Old Man, lots of good info. I took delivery of the
car and took it back 15 minutes later! Lost acceleration on the M62/M6
and noted that the Engine Management Light was was flashing.  All
sorted now, all it needed was a new coil. The mpg seems disastrous.
I've reset the display and will try again on a longer run. What sort
of mpg, mixed town and motorway should I get on a 4 litre?

Cheers

Richard