I did an (extensive) test drive back in March of a '10 X-Premium (US model), and it had the undertray that spanned the entire distance from left to right. I know, because as part of the test drive, I took the Foz to my home, and put it up on my ramps to check access to the oil filter, etc.
I later bought a '10 X-Premium that was not the one I test drove, in April. It has two "mini" undertrays. One on the left side, one on the right. A section in the middle about 24" wide has nothing underneath it.
Weird ... as both were basically the same configuration (X-Premiums, 5 speed manual transmissions, 2010's, etc.)
Same question I had ... in a way, I wish the X that I bought had a full width undertray to provide some level of protection for the underside of the radiator and the lower coolant hose, especially in light of us not having a temperature gauge to "monitor" engine temp in case something were to damage the rad and/or hose.
The other vehicles that we have ('09 Accord and '99 Miata), as well as two in the recent past ('01 Accord and '05 Odyssey) all had full width plastic undertrays. As a "side benefit", their engine bays stayed pretty free of road grime, etc. Can't say the same for the Foz.
my 2006 X has the plastic under engine tray. its huge and covers the whole underside of the engine bay.
i just remove the 8 or so screw clips and swing the access cover out of the way when doing oil changes. its really quite convenient for me and its also nice to see embossed labels of what the supposed access cover is for. :biggrin: