Yeah so I scuffed 2 wheel trims on a Kia picanto.

What’s your guess on what Sixt will try to charge me to replace them?

I’m bagging the £80-100 slot.

not sure, returned one minus a couple of hub caps in spain with no penalty.

Most Hire Co’s have a size limit on scuffs so if they are only small don’t worry.
You can buy genuine Kia Trims for £33.
eBay link
Not sure if they are the same style.
Car Hire Excess insurance costs £40 for a year and covers way more than the overpriced garbage Hire Co’s try and force on you.

Wheel trims, or alloys? Trims, I’d be surprised.

Park that side on the shady side of the car, near another vehicle. I’ll bet they mainly look for paint issues.

You could scrape a swastica into the bonnet so they don’t notice the wheels?

When I used to rent cars in Greece the first thing I always did was take the wheel trims off and chuck them in the boot – saves losing one and getting charged some ludicrous amount to “replace” it – which they never do, of course.