The test can be found here. Doesn't include the Gatorskin but other tests I've seen suggest the Gatorskin is close to the 4-Season.
http://www.conti-online.com/www/down...gp4000s_en.pdf
GP4000s - 34.3 watts
4-Season - 53.9 watts
Both at 35 km/h and I'm assuming that's for 2 tires.