I'd say I get equal reception in my Prius as I do in anything else... Dont know if this helped........... it doesnt suxk tho.
It all depends where you are in relation to the transmitting antenna and how much Effective Radiated Power they are putting. If you a city driver, listening to a station in the city, the shark fin should work fine. However, if you drive say 50, 75 miles outside of the city, you may get marginal results. There are at least 3 variables in play here. The basic rule of thumb, the more signal you want to get into the radio, the more metal you have to stick up. I.E. the Antenna! Ya Gets Whats yaz paysfor!!
I can honestly say that my Prius with the 'fin gets better AM reception than both of our Subarus with stock whip antennae. I can see no diff in FM, good or bad. All things considered, in the LA area where I live it works as good or better than the stock whip. There is a mountain pass where I live where I lose the signal on FM, but both the other cars do too. I bought it to have an easier time using a car cover, and because it looks cool, too. For me its all good, your reception may vary. To test it, temporarily install it with masking or duct tape, and take a drive. If you don't like it, return or Ebay it .
I do a lot of open road driving and in Australia radio cover isn't complete but I find my shark fin as good as the stock antenna on the work Holden, a car designed from the ground up for Australia.