Nice C5 Paul, always liked these versions of the C5. Based on the C6 hence why it is bigger. But yeah, usual result of safety, technology ect ect. Also people getting bigger is one reason why cars are growing. I agree with you though, the interior space does seem on small side for such a large car.
Anyway. I find, when the Xm is on it's belly, it tends to look smaller. When it's up and level, it seems to appear much bigger. But no denying it, the XM is a daintier design now compared to the modern stuff.
Know which one is faster though....

Russ
1992 K reg XM 2.1 Auto SED RP 5712
1992 K reg XM 2.1 Auto SED RP 5705 (D)
Also
2003 C5 2.2 HDI Exclusive
I sell Engine bay, 1990 COTY, Total & Club XM Sticker Decals
http://www.rjwcreativedesign.co.uk