Since we saw the Chevrolet Volt at last year's Detroit show, GM chiefs have been umming and ahhing over when the electric-petrol hybrid will actually make it to production.
But that hasn't stopped them pushing ahead with more hybrid concepts in various shades of green. At Detroit next week we'll see Cadillac's take on GM's E-Flex green propulsion system: the Provoq, a hydrogen fuel-cell crossover concept.
The Provoq uses a drivetrain similar to that in the Honda FCX Clarity - a hydrogen fuel cell and lithium-ion battery combining to produce an electrically charged vehicle that emits only water. The fuel cell develops 118bhp of power, boosted by an extra 80bhp of electrical energy from the battery.
The tricksiness doesn't stop there, though. The power is distributed to both the front axle and also to individual wheel hub motors in the rear wheels, which makes the Provoq genuinely four-wheel drive. Not lightning quick, mind - it'll hit 60mph in 8.5 seconds and top out at 100mph.
But it is green. Caddy says the Provoq will return 400 miles on a single fill of hydrogen. That's 380 miles on the hydrogen tank and 20 miles on pure electric power.
The Provoq features plenty of styling cues from the new Cadillac CTS - all sharp lines and pointy lights. The electrical charging points are hidden within the left and right front fenders, a neat trick that we like almost as much as the front grille louvres that fan open when the fuel-cell stack needs cooling.
Naturally, there are a few eco-concept touches. The roof lining is made of soy (mmm) while the carpets are fashioned of recycled polyester and jute.
But this is, essentially, the forthcoming Cadillac SUV set to rival the BMW X3 when it launches next year. More excitingly for us Europeans, it'll also form the basis for the Saab 9-4X, which will get its own interior and body. No hybrid drivetrain for a while though, we fear.