Well, the nice thing is, even though cars are more complex these days, they're also way less finicky and way more reliable. The downside is, the complexity means they're much harder to repair and often more expensive too. As for stagnating? Eh. It's about creativity and what is and isn't viable. For example, turbo chargers and gasoline direct injection have been around since the early 1900s. Complexity and cost is what has kept them from being widely used until recently. I bet there's something absolutely crazy in development in some lab somewhere just waiting to be tested out on an F1 car or hyper car somewhere. I think the big question, the one that I actually worry about loving cars so much, is how much longer will cars be around for us to marvel at their developments?