If one is speaking of 5-year resale values, nearly every vehicle produced will be a hybrid of one kind or another within the next 5-years. Even Porsche has produced a 911 test mule that will be released shortly, as has Ferrari, and every other brand, that I can think of.

25 to 30 mpg with lithium ion battery packs or a fuel cell powered electric motor will put current vehicles in the junk yards, much quicker than in any time in prior history. Obtaining an effective 30 mpg in an SUV will be the norm, and likely the minimum norm, at that.

Internal combustion engines are not as efficient as electric motors, and one way or another electric motors will be the way in which all vehicles are powered, as we enter the next "generation" of automobile power plants.

As an example, that some of you may be aware of, locomotive diesel trains are actually powered by electric motors 100% of the time. The electricity that powers their electric motors is produced by internal combustion diesel engines, but they provide no forward momentum to the trains whatsoever. That power comes from electric motors only, which are contained in the locomotives trucks, usually in a direct drive fashion.

The electric motor technology is already here: see Tesla Motors. What's still up in the air, is how these electric motors will be powered. For now, batteries are the method of choice due to availability and cost. In the future, fuel cells and other forms will take over, giving vehicles greater range, and allowing them to be more ecologically friendly. Not only do batteries require massive amounts of resources to produce, but they're filled with some vile, god awful elements.

50-years from now, who knows what will power our vehicles. Maybe even 25-year uranium batteries, if they can be produced in a clean and safe manner (using technology that does not exist at the moment). But, I see no way in which any manufacturer will be producing anything but hybrids, if not fully electric vehicles.

From a sports-car perspective, an electric motor makes far more sense as it produces 100% of its available torque in an immediate manner, rather than having to wait 1 or 2 seconds for an internal combustion engine to reach peak torque.

Again, to refer back to the Tesla Roadster. Immediate torque is how it is capable of 0-60 starts in the 4 second range. Put a larger motor in that vehicle, and a higher rated battery pack, and one could see 0-60 speeds in the 2 second range or faster (if you could build a vehicle that was controllable at such speeds: an electric powered Formula 1 vehicle, for example).

Point being, the X5 diesel, is great today and probably the best option throughout modern-day SUVs that the public can now buy. 5-years from now, a vehicle running in dino fuel, only, is going to be a tough sell. 10-years from now, if any of us are still driving our X5 diesels, we'll be in the minority.