In many parts of the world, single-track motor vehicles (in motorcycles above) can also run between or alongside double-track vehicles (in cars above), if there is enough space. This is perfectly legal e.g. in the United Kingdom and the US state of California, tolerated e.g. in France, Germany and Italy, and partially legal (in certain situations - e.g. in standing traffic on the motorway) e.g. in Austria and also in this country (4. I propose to legislate lane-splitting or lane-sharing with another motor vehicle when there is enough space for it and when traffic is moving at less than 30 km/h, with a maximum speed difference of 15 km/h. Safety aspects UC Berkeley study - Motorcycle Lane-splitting and Safety in Califo...
Researchers at the prestigious US university UC Berkeley analysed the safety aspects of this traffic practice and found that motorcyclists who use "filtering" compared to other motorcyclists "are more likely to ride during the week and during the hours when people are travelling to and from work, to use better helmets and to ride at lower speeds. These motorcyclists are also less likely to have consumed alcohol and to have had a passenger. Motorcyclists were much less likely to be injured in accidents while filtering. They were significantly less likely to suffer head, torso, limb or even fatal injuries than motorcyclists in other accidents." (Rice et al., p. 16). Filtering alone therefore does not lead to a significantly higher risk, especially considering that the results detect the same low injury rate up to a traffic speed of 50 mph (ca. 80 km/h) and with the relatively higher speed of the filtering motorcyclists up to 15 mph (ca. 25 km/h), which is significantly higher than the suggested one. filtering alone does not lead to a significantly higher risk of injury than the suggested one. Anecdotal experience of motorcyclists in places where this is allowed suggests that this option makes motorcyclists feel considerably safer, as filtering significantly reduces the likelihood of a rear-end collision, which is a significantly more dangerous accident for a motorcyclist than for a motorist. This experience is confirmed by a 2011 study which found that Californian motorcyclists experience significantly fewer fatal rear-end collisions than motorcyclists in other states.
 Efficiency aspects A study by the Belgian research institution Transport & Mobility Leuv...
Analysing traffic on a stretch of road subject to daily rush-hour congestion, simulations found that replacing just 10% of cars with motorbikes would reduce the time lost in congestion by 63%. This, of course, also means significantly less exhaust pollution. While the study does not explicitly analyse the effectiveness of filtering, it does mention that "when traffic comes to a standstill, it can be assumed that all motorists will be driving between two lanes".
 Health aspects
Unlike motorists, motorcyclists are not surrounded by air-conditioned/ventilated or heated space. The heat on warm days and the cold on cold days thus further exhausts motorcyclists, leading to a reduction in road safety for them and for others. In contrast to cars, many engines are air-cooled, which means that they are cooled by a flow of air over the engine, which only occurs when driving. Standing still or moving extremely slowly in rush hour traffic on warm days is therefore almost guaranteed to overheat the engine, which only adds to the problem mentioned in the previous paragraph.
 
Conclusion
 Filtering is a technique used by many motorcyclists today. Sometimes they are fined by the Police for it, sometimes they even get in the way by a Police motorcyclist. A study by the world-renowned UC Berkeley faculty shows that filtering is actually significantly less dangerous than just riding a motorbike.  A study by a Belgian institution founded by KU Leuven shows that encouraging the replacement of two-track vehicles by single-track ones could significantly improve traffic flow at peak times and consequently reduce air pollution. Of course, in addition to filtering, following the Austrian example, we could also introduce a licence for motorcycles up to 125 cc with a B-category licence after 6 practical lessons in a driving school and at least 5 years of continuous B-category licence (similar conditions are also in place in Portugal, the Czech Republic, Italy and Latvia). Both anecdotal experience and actual research suggest that filtering can reduce the number of fatalities caused by driver inattention.
All of the above are the reasons why I believe that this is a matter that deserves to be addressed and introduced into Slovenian road traffic legislation.