From the Hurricane Research Division FAQ:

Subject: D5) How does the damage that hurricanes cause increase as a function of wind speed?
Contributed by Chris Landsea

Or to rephrase the question: Would a minimal 74 mph hurricane cause one half of the damage that a major hurricane with 148 mph winds? No, the amount of damage (at least experienced along the U.S. mainland) does not increase linearly with the wind speed. Instead, the damage produced increases exponentially with the winds. The 148 mph hurricane (a category 4 on the Saffir-Simpson Scale) may produce - on average - up to 250 times the damage of a minimal category 1 hurricane!

For additional reading, try HRD FAQ

Cheers,
ED