Took a quick run into the basement this morning and looked at the used in original box 1/32 scale MARX XK-E I've got in my collection. They appear to be similar - the factory painted numbers on the trunk are what aroused my suspicion. Mine is red with two white stripes running the length of the hood on both sides, and a number 33 on the trunk, (the side numbers are worn off) the same font as on your car. So... my first "guesstimate" is gonna be the big cat is a MARX. BUT...
Yours appears to be painted, mine is molded in color, and I have seen similar numbers in decal form. The body shape doesn't look the same, MARX was never known for accurate looking slot car bodies, whether they be HO, 1/32 or 1/24. Mine appears more flat in profile, and the door line looks different, too. So... another trip to the basement and I pulled the NOS Strombecker 1/32 scale "Jaguar XKE Racing" body shell kit from the shelf. Lucky for us those boxes weren't factory sealed, so I was able to remove the contents and give them a good looking over. The door line looks more like your model, but the rib running along the top of both front wheel wells was not present (not on the MARX Jag either, for that matter). My Jag is a coupe, but the driver and seat back details on the molded interior insert look different also. Now, I'm thinking -- hey, wait a minute -- what scale is this thing you've got here, my friend? Could it be a 1/24 scale MARX Jag, which could be completely different tooling? I know they made a big scale Ferrari 250 GTO for their "Allstate" sets, but I can't remember what the other body was (it might have well been another Ferrari simply molded in a different color).
So -- ultimately -- is it an ELDON Jag, or maybe a Scalextric? I don't have clean samples of either to compare to, so I can't be certain for sure at this point (after all this morning madness!). Ya sure got my brain (and legs) in gear early on a hot Saturday, though! My friend, you and I have a lot of laughs to share this coming October 4th at the Classic Plastic Model Car Exhibition (in Lawrence, MA). See ya there (and please don't forget that cool MINRA paperwork you found, if you're OK with bringing it out). It's been way past two hours since I started working on this post, so maybe by the time I actually enter it someone else may already have had a definitive answer for us! Hope all this gives you some ideas about your mystery Jaguar. Enjoy! -- Ernie :>)
PS -- Man, what's so wrong with us Americans calling it a 'bonnet' a hood, a 'wing' a fender and a 'boot' a trunk, anyway?
After all, we're Americans, right?! :>) - E