You don’t need a cooler to keep stuff cold in your car. What you need is a fridge. There’s no need to worry about getting or keeping ice anymore, so your food will stay colder for longer.
Forget fancy coolers. If you’re serious about keeping food and drinks refrigerated or frozen over long periods of time, then you need an in-car refrigerator.
Let me explain why.
Refrigeration vs. Insulation
You don’t need ice. That right there is the big advantage of a refrigerator. No ice means more room for food. No ice means no melt, so your food won’t get soaked. And no ice means you don’t need to buy ice when you want to keep something cold.