There is more to eco than mpg, don't beleive everything car commercials tell you. If he runs it on biodiesel most of the time then its more eco than a 40mpg small car using gasoline. I looked at the big picture with my truck, my 20mpg is hald what a small car would get but I'll keep that same truck for 20-30 years where I'd have to replace that small car in 10 or rebuild half of it so its using less resources overall in less maintenance and replacement.