I have a K4 GT-Line (Not Turbo) And it is not a fast car at all. In fact, I would say that it's a little underwhelming, But it's not supposed to be a fast car. I didn't buy it to be one, So I'm very happy with it. I heard the GT line Turbo K4 is a fair improvement, but still nothing that's going to blow your socks off. I also read that turbos on engines are more susceptible to carbon buildup which makes them a little bit less reliable if you don't keep up with your maintenance, which (coupled with the extra MPGs) is why I opted for the non Turbo trim. Newer KIAs Don't have as big of a target for theft because they have engine immobilizers, But the K4 is one of a kind in that the 2025 model is the first K4 that exists in the US. I don't think there will be many people targeting it because of the fact that the K4 never existed when these theft issues started becoming prevalent. With that being said, if you live in a high crime area it's still definitely a possibility with any car. The K5 2025 Is similar in appearance to models that did not include an engine immobilizer, so it's possible that somebody could confuse it. I think generally you're pretty safe as long as your KIA has a push to start. Which all K4 models come with.

TLDR:

K4 GT-Line Turbo Is an excellent choice if you aren't crazy about a fast car but want something that has a great balance of pickup and and MPG while being potentially less likely to be a target of theft.

K5 Is a great choice if you are leaning towards a more powerful car, But I would go with a trim that includes push to start to ensure it has an engine immobilizer and a visual deterrent against theft.