Tradeins are a bit of a red herring, it's not always what you got, but rather what they can afford to borrow from one to give the other. And whether they think they can resell it quickly. Dealers in general hate odd brands, so not surprised. Hyundai gave me dirt (11k) for a very popular Mazda 6 with low kms and immaculate that was 5yrs old. Because it was manual and they knew it would be hard to sell. Mazda meanwhile were after that kind of car. I got 15k trade in and a price I'll never get again on our 2008 RS with a Mazda 323 that was worth 20k less than the 6 was and was 6 yrs old. But they knew they could sell it fast as it was a rare but sought after variant, and it was gone a week later.

Wagons seem to be more popular with Octavias and the RS the most popular of all, especially with the waiting times and the scarcity of them. But the diesel will scare off people.