Lines of code per hour is a bad metric.
Can it solve a problem using production quality code that doesn’t take four times as long to review? That sounds like something I would pay $100 for.
Cost per line of code is not an amazing metric, but at least it's an attempt to come up with a figure.
(I would also be interested to find out how much it costs to run...)
Unfortunately I think things are moving so fast that by the time such a study was done, we would already be on to newer models and newer versions of gas town.