They were mostly related to fuel storage and delivery for a certain segment of vehicles. I'll save the specifics because my employer would be pretty easily identifiable. Ultimately, it's not really relevant; this is common, even in software, where one person stands a chance of single-handedly carrying a product. Maybe there's not be enough engineering time available outright. Maybe the group can't take a risk on allocating resources on a promising idea that might not pan out. Maybe other non-engineering resources in the company are tied up with other projects and can't bring it to market, even if you did pursue it. I'm sure if you think hard enough you can think of multiple products that were genuinely good and had a future, but ultimately died because of a lack of a team that would follow through on developing it.