New station wagon (diesel or gasoline? / Euro5 or Euro6?)

Hello, I am new here and hope that I am right with this topic in this forum. If not, I am grateful for hints. Now on the topic: So far I drive a Volvo V40 D2 (2012). Since in January family growth is imminent and my wife is also driving a compact car, I would like to buy a station wagon. We still have a dog and are often on longer routes in private. Due to the wide distance to work (one tour 100 km, of which approx. 7km country road, 8km city and 8km 5km of motorway) I come to about 40,000 – 45,000km a year. So far I have driven with my diesel half way cost-effectively. But since the topic is cooking quite hot, I am now a little confused and notice that the sale of the Volvo is a bit slow. At the beginning of my research I have seen many great offers for the VW Passat Variant etc.. They had all Euro 5 standard. Now I live rurally and only have to drive 3-5 times a week to Bremen for work. The journeys can be counted on two hands. So far I thought that I could take a car with Euro 5 again. Now a dealer advised me not to do so. Since we are currently building the budget is also limited, so that no new car is possible. Up to a maximum of 13,000 I can look. There is Euro 6 in the combi segment rare. In addition, I want to switch to an automatic transmission. So far I had mostly na because of the kilometers of the year it should already be a car, which is not already at well over 100,000km and can take part for a few years. But I am anything but the specialist and there are certainly other robust engines!? The resale value is rather secondary, but to give away of course I also have nothing and therefore not quite unimportant. How do you see the whole diesel topic? Do you have a tip after what kind of car I am no It would be good if the engine could create the 300,000 (clearly that you can never predict it) I thank you for your tips and suggestions.