Additional to earlier postings, it may be worth mentioning that CFD's will normally be limited to, the range of futures instruments, over which one's chosen CFD provider, offers their contracts for difference, and that whilst there may exist some providers, whose product offerings only include CFDs over "cash" (or "spot") instruments, there do exist, a number of providers, who also offer CFDs over forwards. A few of such providers even include, some CFDs over options contracts, within their CFD product range. As such, expiry dates are a feature of some CFDs.
It is also worth noting that, many (but not all), CFD offerings, are from providers that only offer OTC (over the counter) CFDs. Such providers, typically, enjoy some freedoms with respect to pricing (pursuant to the terms of the clauses included within their customer agreement documentation, PDS etc.) and also operate in a manner akin to a bookmaker by initially acting as counterparty to their clients' trades, and then deciding whether to offlay some, none, or all, of the related exposure, via entry into offsetting positions within the underlying market, and/or correlated/associated markets. Consequently, OTC CFD providers do, at times, have a vested interest in the failure of their clients' trades.
@rcw1, please correct me if mistaken, but may I suggest you review the leverage comparison example, you so helpfully provided, as I am concerned that there may have been an accidental mishap with your calculations.