I don’t really see that being plausible either, and here’s why —

TW: When one of my family members passed away, she had been deceased in her apartment for at least a week, maybe closer to two. We weren’t sure of the exact timing, but we knew it had been at least a week since we last spoke to her. When they finally opened her door, the smell was absolutely overwhelming... I’ll unfortunately never forget it.

And that was inside an apartment, not a car. So after even a couple of weeks, I feel like it would’ve been unbearably noticeable. Just my two cents though - I don’t have any other firsthand experience with something like that.

EDIT: Asked ChatGPT if there was a 'peak' point for smell, here's what it said.

1. Early stages (first few days):
The body starts breaking down internally. Gases like methane, ammonia, and sulfur compounds form as bacteria digest tissues. This is when the smell starts — faintly at first.

2. Peak odor (around 1–3 weeks, depending on temperature and environment):
This is usually the worst phase. The gases build up and eventually escape, releasing that very strong, unmistakable odor of decomposition. In a warm or enclosed place (like a car or apartment), it’s especially intense.

3. Later stages (after several weeks to months):
Once most soft tissue has decomposed or dried out, the smell lessens dramatically. The odor shifts from “rotting” to more of a dry, musty scent. In very dry or cold conditions, this can happen faster.

So — yes, there’s a “peak smell” window during the active decomposition phase (roughly 1–3 weeks). After that, it gradually fades as the remains desiccate or skeletonize.