Dyson make a number of dubious claims.

http://electronics.stackexchange.com/questions/13087/what-is...

http://en.m.wikipedia.org/wiki/Reluctance_motor

The UK regulator of advertising lists a few upheld complaints, and some informally resolved complaints against Dyson.

http://www.asa.org.uk/Rulings/Adjudications.aspx?SearchTerms...