Fair play to Jim McGowan (Letters, Monday) for admitting that he drives an SUV to compensate for being short, writes Frank McNally. His honesty is refreshing, and compares favourably with the holier-than-thou attitude of some SUV critics.
I think we all know the type: people whose emissions of self-righteousness can be dangerous in a confined space or if not filtered through a catalytic converter.
Mr McGowan's desire to "reverse my usual position as one of life's more diminutive creatures" is understandable. In the circumstances, who among us might not resort to wearing platform wheels? Indeed, if truth be told, there may be a similar motivation lurking behind the recent actions of another vertically disadvantaged male: Nicolas Sarkozy.
The French president's latest model is not a sports utility vehicle, admittedly. But at 5ft 11ins, she could equally be considered too big for his needs, when a smaller run-about model would do him just as well.
For all Mr McGowan's honesty, however, moral theologians may be troubled by the contrast between his willingness to pay "any additional charges or taxes" for choosing an SUV and his absolute freedom from guilt about that choice. "Completely unrepentant", he describes himself. Which prompts the question, continuing the religious theme: why be happy to do penance if you don't acknowledge any sin? Such confusion is hardly to be wondered at, I suppose. In seeking to offset the size of his car against his lack of personal altitude, our letter-writer is merely reflecting the dubious morality of the international carbon-trading industry. A precedent for which, as any student of history knows, was the medieval sale of indulgences by the Church.
The papal indulgence scheme started out with lofty enough ideals. At first, a person could gain remission of sins by special acts of expiation, self-denial, or pilgrimage. Then some go-ahead types in the Vatican decided to streamline the system while maximising revenue - and henceforth, the faithful could simply purchase their indulgences under licence.
These were the forerunners of carbon credits. Your soul might be blacker than the inside of a chimney, but pending long-term structural reform, you could pay the Vatican to plant trees for you, as it were, thereby avoiding any post-global warming that God might have had in mind.
The system's infamous height was when it was used to finance the construction of St Peter's in Rome. This in turn was an early prototype for the modern stadium-funding concept in which spectators can purchase a 10-year-ticket while the ground is being built; except that the 16th-century papacy stopped short of offering a premium seat in the after-life's top level. The plenary indulgence merely granted release from purgatory - offer limited to one soul per indulgence.
The controversy reached a head when one of the church's marketing geniuses - Johann Tetzel - brought the scheme to Germany - promoting the indulgences, apparently, with a catchy sales jingle. In direct response, Luther nailed his 95 Theses to a church door. That was 1517; and the consequences were still reverberating on our Letters page as recently as yesterday.
It was bad enough for the Vatican's critics that sinners were encouraged to think they were forgiven without making genuine penitence: a model for the tax on SUVs. But Tetzel's worst crime was to sell absolution in advance for sins not yet committed. Again, unwittingly, he was pointing the way for the 21st-century carbon-trading industry.
The spectre of Johann Tetzel hovered over last year's Oscars ceremony in Hollywood, when - instead of the usual goody-bags full of jewellery - each guest received a voucher for 100,000lbs worth of carbon remission from a specialist environmental company.
Those attending included some of the blackest sinners against the planet - people who fly 747s as a hobby, for example. And here they were being given pre-clearance for another 20,000 miles of driving, plus 40,000 air miles, plus the environmental cost of having a mansion in Los Angeles.
Only the complete cancellation of this year's ceremony - still happily a prospect - would offset that excess. But frankly, I fear this whole offsetting concept is getting out of hand. Which is why, not to hang too much responsibility on his small frame, our letter-writer of Monday has been lured into heresy.
Yes, expecting short people not to aspire to big cars is a bit like expecting the developing economies of India and China to bear the same cuts in carbon production as the US. The problem is that, by the same token, tall people can mimic the US line on carbon reduction, arguing that they can't be expected to drive anything smaller that a SUV, on the grounds that they wouldn't fit.
And where does that leave the average-height majority: those of us who never feel small when walking along the street, but who could not look down on Carla Bruni unless she had her shoes off? Are we the only ones who are expected to drive small cars?