[Gussow's] most oft-quoted statistic is that shipping a strawberry from California to New York requires 435 calories of fossil fuel but provides the eater with only 5 calories of nutrition.
Well, we towed our 5000lb Vanagon across the country (with a rather larger truck than we needed) at about 10 miles per gallon. A gallon of diesel is about 130MJ, or 13MJ per Vanagon-mile, or 2.6kJ per pound-mile, or 5.7 J per gram-mile.
Diesel's energy density: http://hypertextbook.com/facts/2006/TatyanaNektalova.shtml
Google Maps says it's 2906 miles to drive from San Francisco to New York City, which would be 17 kJ per gram. Suppose the strawberry is 20 grams. That's 330 kJ. A kilocalorie, or food calorie, is 4.2kJ, so that's 79 calories.
However, commercial trucking is considerably more efficient. Interstate highways are built to support vehicles of up to 80 000 lbs. gross vehicular weight (40 tons), although much of Europe seems to allow up to 60 tons. http://www.oilcrisis.com/transport/ claims that 18-wheelers get "120 to 200 gross ton miles per gallon", while trains get 750. http://www.answerbag.com/q_view/138616 claims "8mpg when I'm on time; 4mpg when I'm behind schedule," and "4.5 to 7.5 mpg." 4mpg at 40 tons would be 160 gross ton miles per gallon.
But not all of that 40 tons is strawberries; some of it is the tractor and the trailer. One random web page suggests 35000 lbs. for the tare weight. So your 4mpg is hauling 45000 lbs. of stuff, so that's 180 000 pound-miles per gallon, or about 720J per pound-mile, or 1.6J per gram-mile, or 4.6kJ per gram. Or 92kJ per strawberry, which is 21 calories.
Which is one twentieth of Gussow's figure: 21 calories to drive the strawberry across the country, not 435 calories. Maybe there are other energy costs but I don't see how they could add up to 20 times the energy cost of actually moving the truck.
But the train is 4.7 times more efficient (per gross ton mile) and perhaps has a higher fraction of its weight devoted to cargo rather than chassis. If the fraction were the same, a train would bring the figure down to 4.7 calories per strawberry.
Time Magazine's local eating on campus article sidebar says that the average distance is only half that: 1500 miles.
Now, suppose that our calorie per gram of California-to-New-York transport cost is getting spent on transporting rice (5 calories per gram) or vegetable oil (9 calories per gram) instead of strawberries (hypothetically, less than a calorie per gram). Suddenly it looks pretty affordable, energy-wise, to truck those foods all the way across the US if they taste a little better or are a little cheaper.
Boat freight, I think, is even cheaper. Considerably cheaper. Air freight costs more.
What if gas prices go up? Well, if they go up enough, we'll start using rice and corn to power the trucks. But more importantly, they're already only 10% of the cost of the vegetable oil if you truck it from a crushing plant in San Francisco to a restaurant in New York.
What's the tare weight of an 18-wheeler? What fraction of a train is tare weight?