Here's the top ten list:
1. Ford Explorer 4WD
2. Ford F150 Pickup 2WD
3. Jeep Grand Cherokee 4WD
4. Ford Explorer 2WD
5. Dodge Caravan/Grand Caravan 2WD
6. Jeep Cherokee 4WD
7. Chevrolet Blazer 4WD
8. Chevrolet C1500 Pickup 2WD
9. Ford F150 Pickup 4WD
10. Ford Windstar FWD Van
Everything on that list is prime shitbox, except arguably the trucks (because they cost a little much to feed).
What do you think happened to crappy vehicle prices as soon as the program was announced?
Anything that moved and qualified got listed for sale at approximately the same price as the rebate. Hence no more "$500 beaters" (not really $500 by that time but you get the point).
You see the same thing today where the scrap value of catalytic converters drives up the price of the cheapest cars because that's the alternative way of monetizing those vehicles
I don't think this is true. If you look at the cars that were destroyed as part of the CARS program, they don't have a large overlap with popular used cars in the US. The top CARS trade-ins were mostly 4WD SUVs and minivans; the most popular used cars a decade ago were (and are) mostly 2WD sedans.
Another way of thinking about it: the entire point of the CARS program was to incentivize car owners to prematurely (from their perspective) buy a new car by offering them credit for their old one. Combined with the disconnect between the cars traded in and the actual used car market in the US, I think it's safe to say that most of the cards exchanged in the program would not have entered the used market and therefore did not meaningfully impact it by going to the scrapyard instead.