We saw it loud and clear in this year's Jacobs Media Tech Poll III. Most listeners simply haven't actually heard HD Radio and/or don't know anyone who owns one. Unlike XM and Sirius, available through car rental companies, it is actually difficult to sample HD Radio without going into an electronics store. And consumers don't typically buy something unless they know someone who owns one and/or they've experienced it themselves.
You hit 'em where they live. And these days, it's shopping malls. XM Canada has the right idea, working with a company called the Pop Up Retail Group. The latter is a Toronto-based company that sets up kiosks in shopping centers so that consumers can sample XM while they're out shopping.
At this juncture for HD Radio (content aside, of course), it's about sampling. And a billboard isn't going to make you run out and buy a product. Checking it out for yourself at a mall? Priceless.