It was back in November 1974 when I was called to a meeting with our then-Managing Director. He told me about his visit to VW in Mexico and his plans to ‘lend’ me to our customer there for three to four weeks in the near future. Some background information: MANN+HUMMEL wanted to establish a future partnership with our then-licensee, with the aim of manufacturing and distributing air filters with plastic housing and flat cartridges there. The cartridges were also to be suitable for use in different vehicles. To explore the potential of this idea, the very first dust test was approved. At the time, the Beetle type 1 and type 2, and the Brasilia type 102, courier vehicle and type 18 were being produced in Mexico. So, I packed the 45 117 basic filter and various accessories and sent everything to Ernst August Sander who, in those days, was responsible for technical testing at VW Mexico.

An adventure in Mexico

Then, in March 1975, I was told that we had green light to start at the end of April. My first port of call was São Paulo, since that was where the first round paper cartridges were being produced. As I was from development, I was tasked with producing the end plates for the cartridges – back then still made from PVC – and preparing them for series production. It was a very warm week; the workbench was situated in a large hall that also contained the metal presses.

a red and a green car

My journey then took me via Brasilia, Manaus, Bogotá and Mexico City to the VW location in Puebla. That in itself took a lot out of me, but my trip was set to become even more tiring. In Puebla, the VW testers and I picked up the vehicles: a VW Beetle and three VW Brasilias (an estate car specifically developed for the Brazilian market by the manufacturer Volkswagen do Brasil, with around a million sold between 1973 and 1982). Our destination: Hermosillo, the capital of the Mexican federal state of Sonora, which lies around 2000 kilometres north of Puebla! Our task: to conduct the dust tests. The journey to our destination alone lasted three days, and we spent up to 16 hours behind the wheel, almost exclusively travelling on country roads, which were not always well built, and bore absolutely no comparison to what we were used to in Germany. When we finally arrived things, sadly, did not get much better.

yellow car

Our base camp consisted of a small room provided to us by a local VW dealer. It was from there that we were to start our tests. But even the connecting road had such a thick covering of dust that the dust clouds generated when driving far exceeded anything we had previously experienced. The dust collected by the air filters was the same. So, the first tests were soon declared a complete failure: when we removed the filters, the dust billowed out straight away, so we were unable to say with any certainty how much dust had been in the housing and the filters. Quite apart from that, it was already difficult to achieve even half-way accurate results with our portable balance scales. In any case, the peak value stood at 754 grams over 92 kilometres of dusty road.

dusty filter

On top of this, there were also the conditions to deal with – as always with these kinds of tests carried out in extreme heat and dry conditions, with a dust mask covering your nose and mouth, there were some signs of fatigue here and there. Air conditioning hadn’t yet been introduced. So, it was no great surprise that occasionally someone would fall asleep at the wheel and wake up to find themselves in the irrigation zone at the side of the road. Usually, the unfortunate driver would be given the chance to get their vehicle back on the road themselves. Now and then, however, nothing could be done, for example, if the tow rope failed because it was missing an eyelet. In those cases, it was simply a matter of waiting for the tow truck. And how do you pass the time until it arrives? You keep your eyes open and have a look around.

a snake on a stick

One time I found a small snake and picked it up with a stick to show everyone. Our Mexican colleagues immediately retreated to a safe distance, claiming that this was a highly venomous viper that was also capable of jumping up to three metres! As the snake had wound itself around my stick, I thought that this was technically impossible but, nonetheless, I was happy to let it go and continue on its way. After that, the Mexicans refused to continue working without the right boots.

Heinz Mueller the 1970s

Once we had sourced some proper footwear, the remaining days passed by in a flash. In mid-May, Ernst and I flew back to Puebla and had a final meeting with the VW representatives and our licensee and two days later I was on the plane back to Stuttgart. What was the result of the tests? The 45 117 54 was one of the first flat cartridges to be introduced worldwide by MANN+HUMMEL, and was sold for many years in Germany, Mexico, Brazil and Argentina. Ernst and I have built a genuine friendship since those days, even surviving his move to Seat. We still regularly speak to each other all these years later.