Diesels seems to be on the way out. Not only because of cheating, but also the issue of diesel particulate filters being f***ed up by urban driving patterns, with expensive replacement jobs. I can only find one journal paper about diesel-pentane blend which reported up to 18% reduction in NOx emissions. Now diesel engines with "LPG conversion" actually burn mostly diesel and
20-25% propane. This results in very little soot in the exhaust. I am curious if pentane would also reduce the soot. Although, it is probably not practical solution, as refineries would have to produce more pentane, which is around $2 a kg for a tanker load.