Single Product Website or Multiple?

I'd like to get some opinions regarding website seo. If a current website is seeing good traffic with a primary product of Medicare Supplement Plans for several years, then a new product is introduced, for example; auto insurance (different demographic) with plenty of content over a 9 month period, with virtually no traffic.

Should the new topic have it's own website or blog, or can it be incorporated with the original website?

Thanks.

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