Don’t know what to do (financing vs. leasing)

Since I know that when it comes to deciding whether to lease or to finance better, the situation is always important, I now ask for advice and try to describe my situation: Current car: Astra G 1.6 Petrol Kilometers per year: approx. 25000 – 30000 Current KM-Stand des Autos: 120000 The mileage is related to my work. However, the route is mostly motorway. Since I have between 200 and 300 Euro petrol costs per month, a diesel would be very interesting for me. J I was with my dealer today and he currently has annual cars of a former company there. That would be an Astra H (Diesel 1.7) with approx. 10000 km. He would sell them for approx. 11.000 €. I find this is a very good offer. Then we looked at the car and then he suddenly said to me: “Why do you throw out the money like that? Do leasing. That goes with 0 € down payment and a leasing rate of approx. 200 €/month. After that you can leave the car again. And they ha You have a full guarantee and nothing can happen. Be honest and think about how much money they have already invested in their used cars. Why should you do that?” <-- sounds really good and reasonable. Now the question arises, why does he say something like that? Because he wants to/must or because it is really more meaningful? My income is about 1400 € net per month, whereby quite a lot is deducted (apartment, Ben) zin, insurance etc...) So I don't have much money left. The money I have is 3000 €. And even the money I get for my old car (estimate about 3000 € again). That means I would have 6000 € available. My question that I'm asking now is: Well, with 6000 € I could lease a good 2 years. On the other hand, I could invest the money in the "new" used ones and maybe finance the rest for 2 years, but then it would be my own. Or should I really drive my current car to the bitter end? For the next few years I will have to drive these routes and drive so many KMs. Maybe someone has a tip, because I don't know very well about this, am unsure and always break my head.