For sure
Bank loans I'm guessing will be less accessible now too so the used car market will slump and slow dramatically I suspect
I don't think the used car market will slump that dramatically as a whole
The issues of high % impacts all car purchases, so will reduce the supply of used cars massively, keeping the prices up.
And as a lot of people are on time limited PCP deals etc there is always a demand to change.
What you will see imo is a huge change in what cars people can actually afford, and a big drop off of premium vehicle sales (new and used)
The rate rises will hit all but top few %, so even the top end of the middle class will be downsize/downspeccing like everyone else.
As always the 'rich' will be completely insulated from the whole thing, with low volume high value cars carrying on basically as normal.
I'd expect that what will happen for the market as a whole, is that demand will focus a couple of tiers lower on the model range than it does currently for most brands, and 'budget' options like Dacia/Kia etc will gain LOTS of market share.
For the long term, it will depend on the stability of rates as to if the manufacturers actually lower the prices or change model specs etc.