In 2018 and 19 rupee had already depreciated a lot, yet used car prices were mostly stable. In late 2019 used car prices started taking big jumps.
My point is that used cars had never been value for money in pakistan. Even before extreme rupee depreciation, used car depreciation was rare, you must remember the old adage of corolla and mehrans being hard cash, because they never depreciated even before tabdeeli. 2018 and early 2019 were special cases in a sense that new car prices increased a lot, but used market did not catch up, especially for undesirable cars. Plus there were always special cases of undesirable cars depreciating hard. Which is not the case anymore, there is not a single undesirable reasonably modern used car. And because of that, buying used cars does not make sense anymore.
You bought rebirth at a great price, I regret not getting a used rebirth back then. But that does not mean that used rebirths are a great buy anymore with the extreme appreciation in their prices.
Another example are 2010 model e200s. I remember they were around 5m in 2015/6. Now they are around 7.5m. So 50% appreciation for something that has been used and abused for 5 more years, let alone the horrible reliability repute of 10+ years old benzes. Rupee appreciation in my opinion cannot explain that appreciation. Market dynamics and people's buying preferences have changed for the worse.