Must be. It was also amazingly quiet when it taxied in.
I don't have the slightest idea what 100LL avgas is priced at now nor diesel for that matter, but I suppose it could be a money saver if you don't mind leaving a smoke trail.
Modern diesels don't really smoke that much, and as Puma noticed they're pretty quite too. Unlike the Detroit Meatwad would like stuffed in there. Of course with a Detroit it would no longer be capable of flight, but it would be one heck of a hedge trimmer Sik
Around here, 100LL has been in the $5.50ish range, +/-.