A barrel of oil contains 42 gallons, and has the energy equivalent of about 7 million British Thermal Units (BTUs).

Not to get into too much of a science lesson, but one BTU is enough energy to heat one pound of water from 39F degrees to 40F degrees.

So we don’t care about whether that oil is in a barrel, in a pipeline, whether it’s black and sticky or light and sweet. We care about those 7 million BTUs. The energy is what we’re buying when we fill up the oil tank ahead of a long winter, or we gas up our cars to drive to work. It’s the energy that matters – and although oil, a stable liquid, tends to be a more convenient form of energy than say, a pile of electrons, a campfire or a bowl of oats – it’s the energy that we’re paying for.

I don’t know what kind of premium we pay for the convenience, but at some point, that convenience premium will get superseded by a variety of other, inarguably cheaper energy sources.

We might quietly scoff at the Toyota (NYSE: TM) Prius drivers - after all, the car only gets slightly better mileage than the average car in its class, so it's not all that special as far as environmentalism goes.

But don't scoff too hard, because it just might be that we'll all be driving hybrid cars in the not-so distant future.

You might be thinking that we simply don't have a model of fuel-source change for automobiles - so we really don't know what the future will hold - and whether our cars will be powered by natural gas, lithium-ion, or even solar power - or perhaps some combination.

And you're right - there's basically no model for automobile fuel conversion.

But there is a very robust model for home heating conversion.

Today there are at least as many heating technologies as there are fuel types, but 100 years ago, most people used coal and wood.

Group 1 Automotive, Inc. (NYSE:GPI) CEO Earl Hesterberg said the auto retailer will close underperforming stores going forward. The firm plans to incur between $10 million and $15 million in closing and related costs during 2008. Hesterberg made the comments during a morning conference call.

Along with negatively impacting sales, the CEO said the auto industry’s slowdown has hurt the firm’s inventory levels. New vehicle inventory grew to 71 days’ supply from 63 days a year earlier.

“We need to reduce our truck inventory in the second quarter,” Hesterberg said.

The Houston-based company announced before Tuesday’s opening that its first-quarter net income slipped to $16.4 million, or $0.73 per share, compared with $17.5 million, or $0.72 per share, a year earlier. Wall Street analysts anticipated earnings of $0.68 per share.

Quarterly revenue increased slightly to $1.53 billion, compared with $1.52 billion a year earlier. The revenue results also beat Wall Street’s expectation of . . .

It’s been a long and sometimes rocky road for Hayes Lemmerz International (Nasdaq: HAYZ) since its founding companies manufactured wood-spoke wheels for Henry Ford’s Model T. The Northville, Mich.-based maker of steel and aluminum wheels has survived the decline of the Big Three automakers in Detroit and a Chapter 11 reorganization earlier this decade, and now seems on track to reap the benefits from its concentrated effort to restructure operations and restore profitability.

The company earlier this month announced solid gains in sales and earnings for the first fiscal quarter ended April 30, and said it was on target to reach full-year goals of $2.2 billion in sales and $200 million to $210 million in EBITDA, compared with $2.06 billion and $188.6 million in the year ended January 31.

Hayes Lemmerz is the global leader in supplying steel and aluminum wheels to passenger cars and steel wheels to commercial vehicles. It has had a laser focus in the past couple of years in positioning itself in the global automotive market and now realizes three-quarters of its sales outside the United States (and four-fifths of its wheel sales). While it still depends heavily on the Big Three in the Unites States, it has won virtually all the major European and Asian carmakers as customers as it shifts production to low-cost sites in Czech Republic, Turkey, Thailand and India.

At the same time, it has shut down and sold off non-core operations in the Unites States  and in general downsized the company, going from 43 facilities and 11,000 employees when it emerged from Chapter 11 in 2003 to 30 facilities and 8,500 employees now. Of those 30 facilities, only seven, with 1,500 employees, are in the Unites States – the remaining 23 facilities and 7,000 employees are spread among 13 foreign countries. Wheels, which represented two-thirds of sales in 2003, are projected to account for 84% in 2007. Other products include components for brakes and powertrains.

The company followed up its operational efforts with a successful capital restructuring this spring, raising $180 million in a rights offering, plus a $13 million direct investment by manager Deutsche Bank, to retire senior debt. It consolidated the rest of its debt in a $495 million syndicated loan and a $175 million euro-denominated note offering in Europe, so that the end result is to slash $24 million annually from its interest expense ($76 million in the past fiscal year), extend maturities (the earliest now is 2013), and better match its income streams.