Diesels seems to be on the way out. Not only because of cheating, but also the issue of diesel particulate filters being fucked up by urban drivingpatterns, 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.