When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The engine compartment has several plastic panels that have ¼ or ½ turn screws that hold them in place.
I need a handful of the sockets that the screws engage in.
what are they called? Trim fastener Trim fastener
They called "Quarter turn nut AGU2643" and you will be quite surprised on price... People use cage nuts and regular screws as an affordable fix. M5/M6 size fits pretty well.
Nylon mushroom screws will look pretty much stock BTW.
I replaced some of these with the accompanying plastic quarter turn screws when I first purchased my x300. From memory I think I purchased then from SnG Barratt many years ago and have since lost a couple more. I don't think they stock them anymore but may be worth a look. After some quick googling I've just found some cheap alternatives on Amazon.
I lost a couple of the nuts into the abyss behind the headlights several years ago and after I got my replacement nuts I glued them into the hole so they don't fall out.
I replaced some of these with the accompanying plastic quarter turn screws when I first purchased my x300. From memory I think I purchased then from SnG Barratt many years ago and have since lost a couple more. I don't think they stock them anymore but may be worth a look. After some quick googling I've just found some cheap alternatives on Amazon.
Just like you I replaced my radiator mounts and while I had the top panel removed decided to replace the missing quarter turn panel fixings.
I was not surprised that the Jaguar price for these was extortionate for a plastic fitting that should cost pence. Many British cars use similar fittings as you have discovered, but the Jaguar fixing is not a standard size. I bought some standard ones from bresco.com (QTC006P £9.99 for a pack of 19 - shows how much they should cost ).
They are slightly larger and I simply enlarged the panel holes to fit (12.6mm x 12.6mm).
They work with the original Jaguar quarter turn screws that are fitted to the plastic covers and sit slightly higher on the panel than the Jaguar ones but do the job well.
What are these twist lock sockets called?
Nothing a pencil file can't fix 
).
