Mine also is most noticeable in a closed garage after 10-15 minutes.

I changed the plug tubes after I first noticed the smell last summer, because I was getting some leaking. There is firm oil/dirt mixture on the bottom of the cam cover edge, which I've tried to clean off as best as possible. No residue on top of the cat that I can feel (I can't see anything with a mirror but honestly it's hard to tell).

I took apart one rear brake to have a look at the park brake. Looks good. I set up the park brakes to get the four clicks. Will check for smell again. Don't honestly think this is the solution, but we'll see.

Hey Martin, I know the smell you mean, this isn't that.

also check your cv boots - they might be throwing some grease at high speeds. another place to look on the 5-speed is where the shift linkage enters the transmission case - you can get some weeping there as the bushing develops play over the years. or, rms weeping enough oil that it gets on the clutch but not enough to show on the bottom of the engine/transmission interface.

Clickman, did you ever find the cause? I recently had my cats replaced and ever since I have an overwhelming exhaust smell in the cabin. It's so bad I can't drive the car. Based on your description I'm wondering if we have the same issue.