Ideas to increase radio reception?

That's odd, my Canadian Prius also has the Premium JBL sound system, and it appears to have very good reception FM. I never listen to AM so can't comment on that.

Have you unscrewed the antenna to check for corrosion? I like to put a dab of silicone dielectric grease on the threads before screwing it back in.

If it has never been off, you may need pliers to unscrew the antenna. Make sure to wrap the antenna base with a rag to minimize scratching it.

 

There are antenna amplifiers that you plug into the antenna line and a 12v source. I have used them in the past with mixed results. Google shows:
<http://www.shopzilla.com/7S--Car_Accessories_-_cat_id--11950000__keyword--car%20antenna%20amplifier__lp--10__mkt_id--20561806__rf--gsz__sfsk--3>

 

there are so many factors that go into good reception, it's hard to know the culpret without having some specs on the head unit itself. is the problem signal strength? the antenna is amplified but perhaps not enough. is it capture ratio...the ability to pull & lock in a station? is it rejection...the ability to tune out interference. so many possibilities.

i've had saabs & VW's recently...and both provided basic stereo specs in the owners manual. this is the first car that doesn't offer anything tangible. no wiring diagrams, no specs. it's frustrating.

i have the basic stereo model without "diversity tuning" and the reception is mediocre at best.

 

This must be one of the deficiencies in a Prius. We noticed the same thing driving the Prius home from the dealership. Stations we receive routinely driving the Subaru were mere static. My husband is going to check out the antennae to see if he can replace it with a longer one.