"Dios es mi piloto (God is my pilot)," the sticker above the driver's head proclaimed as he bombed along the serpentine edges of precipices and ravines several hundred feet deep. Through the gloaming we charged at speeds suggesting our pilot wanted to be discovered as Grand Prix material.
The bus companies put drivers under the hammer of unreal deadlines which they must meet to keep their jobs. So our driver leans on a klaxon fit for the Santa Fe express, narrowly avoiding oncoming articulated mammoths as we sway past slower coaches in the nick of time.
Now I know why those little shorts appear from time to time in our World News pages: "60 die in Guatemala bus crash". The bus will have been carrying almost double the legal US limit.
The eight-hour journey from the northern frontera with Mexico is almost all through folding highlands, at times over 8,000 feet. Words like eerie and surreal come to mind in this startling landscape, trees fringing the summits, which has been the scene of dreadful atrocities against the diverse indigenous peoples. During some 36 years of guerrilla war that ended only last December an estimated 200,000, mostly Indians, died.
Now Guatemala has an absence of war, continuing highly visible poverty and rising violent crime. I had been warned not to travel at night. But all that did happen was that black uniformed police with sub-machineguns boarded one of my many buses, silently prodded passive passengers, gave a speech about a search for fugitive "narco" criminals from the capital, and waved us on our way.
Perhaps mindful of past roadside atrocities by the now allegedly reforming forces, the officer's speech sent a ripple of mirth through the bus, but only as we accelerated away.
The change at the Mexico-Guatemala frontera is not, as the song says, one from major to minor: more like minor to B flat. For two territories that were once one mountainous geopolitical entity under Spanish rule, Mexico's southern state of Chiapas and Guatemala are today difficult to move between. In several days of road travel over 25 hours, 22 modes of transport had to be employed.
Most Guatemalans, of the Mayan family, are small. At least three can fit on benches intended for two. The aisle between can take another two with one cheek on the seat's edge and the other supported by the cheek of the passenger on the other side. Altogether eight sardines in a row meant for four, plus the odd breast-feeding infant blissfully ignoring the potholes.
Even more are squeezed in as the driver insists on picking up absolutely everyone who hails him. But that is all they stop for and there are no toilets. On the one better-class bus I boarded the "washroom" was firmly locked, to no one else's disappointment.
Saving yet more passenger space is the roof rack, which Ireland last saw on 1950s provincial buses. Here campesinos (peasants) travelling long distances for work throw up their hundredweight bags of bananas, grain or whatever. Most camionetas - as the Guatamaltecos call buses - looked as if they have already led a full life as school transport in Knoxville, Tennessee. Some even appear in their original yellow "School Bus" livery.
A word of praise for the Mexican bus system and roads. Having travelled this year from Tennessee, by the Alamo and troubled Chiapas, to Guatemala City by bus, I can say that the prevalent First World impression of chickens packed in with Mexican campesinos is wide of the mark. In fact the better Mexican buses are superior to the Greyhound.
In chaotic Guatemala City, home to four million souls, the central zocalo (square), with imposing presidential palace on one side and cathedral on another, has paved roads around it. A demonstration was in progress. Graffiti said: "Privatisation - more poverty".
The papers were full of Guatemala's (officially waived) right to claim neighbouring Belize and President Alvaro Arzu's attack on the media at the Ibero-American summit in Venezuela. They kill journalists in Guatemala.
I quickly found the Franciscan Iglesia Imaculado Corazon de Maria and its parish priest, "Alfredo" O'Loughlin from Limerick. This radical priest has spent almost half of his 56 years in Central America. Essentially all the Indians got from the peace agreement was the right to exist and to repatriate their thousands of exiles in Mexico, he told me. But the former rebels are going into politics. However, a rash of unexplained lynchings of prisoners taken from jails has followed "the peace", he said.
At a fiesta that night he sang Buachaill on Eirne Me and Molly Malone to wild applause. The feeling of security in the church enclosure almost made me agree with the ubiquitous bus drivers' stickers: "If God is with me who can be against me?" It's easy to see why for Guatemala's long-suffering poor "Jesus [and not politics] is the only solution".