who only burns five gallons per week? I didn't do that when I lived a mile from work! I burn a tankful of gas (14 gallons) per week, maybe a tad more, and most people have longer commutes than I.
but even if we use your figures, one acre per car per year, there are how many cars in the US? 150 million? how soon before you can have a significant portion of that acerage in production?
I burn 10 gallons every 11-12 days. I have a 17 mile commute, 1 way.
Did it occur to you that many, many people might buy smaller commuter cars if they got 50 mpg and the fuel was naturally produced?
Did it occur to you that we might have a MIX of cars on the road, daily commuters going bio-diesel and weekend vehicles using petroleum?
Not every vehicle has to run on the same type of fuel.