To be fair, the Prius was one of the rare cars in its class and price point with LKA at the time (2009). I believe Lexus vehicles with Lexus Safety Sense (1.0) did have LKA but not all of them. So I guess for some Lexus owners who upgraded, it was the same for them. On which vehicle? The "following" part is just distance control. i.e. it follows the preceding car's speed to maintain the set distance between it and your vehicle. It doesn't follow it around the curve unless you have LTA.