Light output is measured in lumens, or candlepower. Watts is an electrical unit. The fluorescent household lights put out a lot more light per watt, but this technology isn't in use in H4 bulbs.

My impression of the "halogen" technology was that a halogen bulb was good for maybe 10% or so more light per watt. I wonder what technology gives 50% more light output.

I'm assuming these new H4's still use a tungsten filament... can a different filament design or some special gas inside the lamp make a 50% difference?
I don't know...

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Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic