Once the decision had been made to offer V8 power, the challenge for Volvo engineers was to figure out how to squeeze those two additional cylinders into the tight confines beneath the XC90's hood. Add the fact that this would be the first eight-cylinder engine in Volvo's 75-year history, and the company decided to seek outside help.

They found it in an unlikely place: Japan. But with decades of experience making pint-sized powerplants for motorcycles and having built a similar V8 engine for Volvo's parent company Ford in 1996 (for the Taurus SHO), the engineers at Yamaha know a thing or two about designing powerful engines that are still compact enough to squeeze into small spaces.

The V8 engine that sprang from this collaboration between Volvo and Yamaha is a bit unusual. For starters, the engine features a 60-degree angle between its two banks of cylinders (compared to the more familiar 90-degree spread of most V8 engines). The two cylinder banks are also offset from one another by the width of half a cylinder to clear the XC90's existing crossmembers.

Shoehorning the V8 into the XC90's engine bay also required relocating space-stealing items like the alternator and starter motor into unused voids on the engine itself. The whole arrangement was then mounted transversely (sideways) so as not to interfere with the energy-absorbing crumple zones built into the XC90's body.

At less than 30 inches long and just 25 inches wide, the result is the most compact V8 engine on the market. Weighing in at just 419 pounds, the all-aluminum motor is lightweight as well, making the curb weight of the XC90 V8 identical to that of the six-cylinder T6.