In 2011 a particle number (PN) limit was introduced in the European Union’s vehicle exhaust legislation for diesel passenger cars. The PN method requires measurement of solid particles (i.e. those that do not evaporate at 350 °C) with diameters above 23 nm. In 2013 the same approach was introduced for heavy duty engines and in 2014 for gasoline direct injection vehicles. This decision was based on a long evaluation that concluded that there is no significant sub-23 nm fraction for these technologies. This SAE paper (2015-24-2512) examines the suitability of this PN method for L-category vehicles (two- or three-wheel vehicles and quadri-cycles).