Vehicles do not come with pituitary glands.

They don't slowly grow from one form to another, undergoing painful transformations and Peter Brady voice changes.

They follow a more Darwinian path, evolve or die.

As Cadillac continues with its evolution, it has adopted a more family look throughout its lineup. Now, it can welcome the 2010 Cadillac SRX into the fold.

The five-passenger luxury crossover sheds its squared-off corners for a curvier body, creates a more luxurious interior and beefs up its performance. This is a crossover capable of never slipping on ice and stealing some customers in the growing luxury five-passenger crossover segment.

With the addition of the SRX and Audi Q5 taking on mainstay lux crossovers, such as the Acura MDX and Lexus RX350, this crossover group has gotten a lot more interesting. No one seems to be taking customers for granted.

The Crest and Wreath brand finally seems to be taking the competition seriously, or more to the point, the competition may start taking the SRX seriously.

It should. The SRX comes with a great little 3-liter direct injection V-6 that provides 265 horsepower and 223 pound-feet of torque. In the fall, Cadillac will offer a 2.8-liter turbocharged V-6 that will tip the power scales at 300 horses. Providing good power helps the SRX roll through hills and highways with ease.

Power for the sake of power has slowly gone out of vogue -- and I am not condemning that notion -- but a crossover doesn't need M1A2 Abrams torque or Bugatti Veyron top speeds. It needs enough power to make the driver feel comfortable merging onto the highway with a cabin full of kids. It needs to always have a little left in the tank -- just in case.

The SRX can be speedy if it has to, but it feels more comfortable cruising along at 80 mph or gently rolling through the Irish Hills. In tests of both the all-wheel drive and the front-wheel-drive-only version, I preferred the all-wheel drive model, especially when driving on twisty roads. It felt more responsive when you pressed the throttle and had better manners through turns.

The SRX's sportiness falls somewhere between the Lexus and Audi -- sportier than the RX350 but not as sporty as the Q5. My biggest issue with the vehicle's power was that it required you to goose the gas to push up the rpm and pull out the power in it. The six-speed automatic transmission wanted to get to sixth gear in too much of a hurry -- which transmissions sometimes do when trying to improve the vehicle's gas mileage.

The all-wheel drive system, developed with Haldex, uses an electronic limited slip differential that allows the system to transfer the torque quickly from front to back and from wheel to wheel. In a test at General Motors Corp.'s (hey it was Corp. when I tested it) Milford Proving Grounds, I parked the SRX with the driver's side wheels on wet ceramic tiles to simulate ice and the other two wheels on pavement. Gunning the throttle, the SRX jumped forward, the slippage unnoticeable.

While it's not likely you'll find yourself parked half on ice and half on asphalt, the demonstration shows how capable this Cadillac has become.

There were some significant improvements in ride quality and quietness over the outgoing model, and the interior makeover is the SRX's most impressive visible feature.

Following cues from the CTS, the SRX wraps the driver in leather and surrounds her with useful technology. Bluetooth connectivity for hands-free phone operation is standard and the optional pop-up navigation screen rises out of the dash at the driver's command. When recessed in the stitch-accented dash, the screen still glows with information. And if you don't have the navigation system, the SRX comes with GM's OnStar plan with turn-by-turn navigation, which allows you to call an operator for assistance. Additionally, the ambient lighting in the cabin adds an additional luxury at night.

There's continuity throughout the cabin in a well-crafted dash and instrument cluster. The touch points -- the door panels and center console -- are soft, so the driver will never feel uncomfortable. Whether on a long trip or just errands around town, the SRX provides a pleasant atmosphere.

There are also some nice features, such as the hidden cargo management system in the back under the floor of the cargo area. Additionally, the liftgate can be programmed to stop at different heights to help shorter people who can't reach it when it's all the way up, or to avoid hitting a low-hanging garage door. It's a feature you never knew you needed but now have to have -- and that's what luxury is all about.

Cadillac has also added to the SRX's safety features. Aside from the front and side-curtain air bags, there are front-seat-mounted pelvic-thorax air bags -- a feature we're going to see more carmakers add to their vehicles. The SRX also uses martensitic steel, one the strongest steels available, in places on the body to help absorb damage during side impacts.

I have still not warmed to the exterior. I liked the original better, with its straight-laced sides and flat top. The new SRX looks as if Cadillac overinflated a CTS. There's a strong vertical theme with the 2010 model. The tall headlamps in the front (which turn with the steering wheel) and the even taller tail lamps frame the vehicle in oversized lighting.

The big grille is more aggressive and denotes the sportier character of this vehicle over its predecessor, as if to really, really make sure people know that this new vehicle is different.

However, the curvy roof line makes the SRX look too much like other crossovers on the market.

Part of the success of the CTS has been its individuality, the way it looks so much different than anything else. The SRX doesn't possess the same feel. It's good-looking but feels much less original.

However, it's distinctly a Cadillac, and that's not bad company to be in.

Improving generation after generation is much better than the opposite, and the SRX will continue to evolve, which is also much better than the alternative.