More power or more money? That's the age-old dilemma that faces so many car buyers these days, and nowhere is it more keenly felt than when shopping for the BMW X5. That's because drivers need to choose between the less-expensive and under-powered 3.0si model with a V6 engine and the pricier, more powerful 4.8i version with a V8. The price difference is almost $10,000, and the V6 offers better fuel economy. What to do?

Well, a certain cross-section of the population will say that the right thing to do is not buy any fossil fuel-burning car at all and get a bike or a horse instead. Fine, that's cool. We love the planet, too, but don't think that this is a real option for most people. (Imagine taking your kids to hockey practice on a bike.)

No, most people will wrestle with their conscience and their bank account, and come up with the answer. Maybe we could help out a little. If you're contemplating the X5 and can afford the 4.8i, our advice is pay up for a better car.

Here's why: The V6 version, which starts at $45,900, gets a measly 17 mpg in the city and 23 mpg on the highway. That's pretty much in line with every other midsize spot-utility vehicle on the marketand yes, we know BMW likes to call it a "SAV," or "Sport Activity Vehicle," but that smells like a creature of the marketing department rather than the engineering department to us. The 4.8i, which has a MSRP of $54,500, however, gets a slightly worse 15 mpg and 21 mpg, respectivelybut with so much more power. Since the difference in fuel economy is negligible, why not have more fun driving?

Since its introduction in 1999, the X5 has been a hit for BMW. At a time when SUV sales are down, sales of the X5 are up. In fact, it remains BMW's second-best-selling product line in the North American market, after the entry-level 3 Series . For the first three months of 2007, BMW sold 9,069 X5s, up more than 26% from the same period last year. To put that in perspective, over the same period, sales of Ford's ( F ) redesigned and commendable Explorer , the one-time king of the SUV market, sank 25%.

Still, BMW lags the $37,400 Lexus RX 330/350, which sold more than 6,600 over the same period. However, that number is off 4% from the same period in 2006.

So what makes the X5 such a hot ticket? To find out, read on.

Source: [url=http://www.businessweek.com/autos/content/apr2007/bw20070427_499041.htm?chan=autos_auto+reviews_auto +reviews]BusinessWeek[/url]