My 2.2 tonnne Ford 4wd gets 25 mpg. My 1 tonne Ford Escort (1973) got .... 25mpg. Your mate is wrong. When I first got a company car it did 12 l/100km. 25 years later the same model of car was grtiing less than 9, despite 25% more par, and meeting tighter emissions regs. Your mate is wrong.
You're clearly not talking about American cars. What's a 1-tonne Ford Escort? I did have a 1983 Dodge Ram D150 half-ton pickup truck with a Slant-6 and an A-833 manual transmission; that thing would get 25MPG and hold 75MPH all the way westbound across Michigan... of course, it took it a while to get to 75MPH, merging was just like driving a Peterbilt with a 53' trailer full of anvils. That exact same engine and a comparable transmission were available for the Dodge Trucks line from 1960 to 1987 and was renowned for durability and reliability.
The key point is that Americans typically don't want them. To this day, in Canada, gasoline is cheaper than water. I'm not sure if that's a statement about gas prices or a slam against the sort of fool who feels the need to buy their tapwater in PET bottles, but I digress. So people buy horsepower. People buy large vehicles based on truck platforms.
As CAFE forces vehicles to become more fuel efficient - without addressing the underlying consumer demand problem! - manufacturers are being forced to use smaller and smaller engines. This means adding turbochargers to cute little aluminum blocks, narrower cam lobes and variable displacement oil pumps and smaller oil control rings all to reduce the internal drag, and thinner oils which offer zero cushion on connecting rod bearings. All of this gets stuffed into a full-size pickup truck with a trailer hitch. They're intolerant of real-world conditions and use, and because of their complexity they're expensive to repair. These vehicles will not have a long lifespan - sure, you might get a good fleet average mileage, but if 50% of the vehicles don't make it to the 100,000 mile mark, they're getting replaced faster with all the environmental damage of producing and disposing of the vehicle.
Maximizing vehicle life is an important part of reducing the vehicle's overall environmental impact.
There's a great YouTube channel where the owner of a full-service used auto parts business takes apart modern engines and shows you what failed. No prior knowledge of engines is required to understand this. Some engines are spectacularly broken. And Eric talks about what will last, and what won't, with an entertaining sarcasm.
Recycling? The lead-acid primary battery gets removed, then the car gets crushed and shredded. Only the steel and the aluminum get recycled. Anyone who thinks that any other material in a car gets recycled in any quantity has never seen a car shredder in operation. ASR (Auto Shredder Residue) is a special waste stream now consisting mostly of mixed plastics, smashed safety glass, and the crap people leave in their cars when they junk them. All that plastic gets landfilled.