Mom's view: Neither, thank you very much. Both have poor visibility to the side and rear, although the Porsche offers a sonar system that has a great dashboard light alert system letting you know how close you are to things in back, in front, and on the side. This is a most wonderful feature. Both vehicles gulp fuel at furious rates. We averaged about 14 mpg in the Cadillac and12 mpg in the Porsche. Fortunately, the Cadillac enjoys regular while the Porsche needs premium. There is a faster, twin turbo Porsche Cayenne available, but we elected not to test this model. Moving nearly 5000 pounds of tall SUV down the road with 450 refined horsepower at your disposal wasn't something The Car Family could justify with its high fuel consumption and insurance premiums
The Porsche was better handling, had easier to read gauges, was quieter and quicker (not faster), but was more difficult for me to live with. First off, the remote key never worked properly. In nearly 15 years of doing vehicle reviews we never had a car when the alarm went off so frequently. The interior locking system acted so defiant causing us to spend a considerable time reading the owner's manual. Yes, even my husband read it so great was his consternation. If nothing else you have to be nearly next to the Cayenne for it to work and secondly, unless you use the main menu option that allows you to open all the doors at once, you most likely are going to find it faster to just open the door with the key, reach in and press the manual door opener for the rest of the family to gain entry.
As an aside, good luck understanding the inflatable spare tire removal operation. The Porsche was the only car manual we have seen that informed the reader how to remove the key from the ignition when the battery went dead. Makes you wonder if the Porsche has had electrical problems or if the German engineers are just being thorough
In case you are wondering, the key to removing the key, literally and figuratively involves using the screwdriver from the spare tire tool kit and some good eyesight.
To fill the Porsche's 26-gallon tank required nearly $70 and we had to fill it before we had gone 300 miles. The Cadillac was more fuel friendly, although it is largely the lesser of two gas-guzzlers, returning about 14 mpg. At least you could put regular in the SRX's tank.
Neither car was a joy to park as they have large turning circles, but at least they were exceptionally easy to get in and out of thanks to the fact they were not too high off the ground. The Porsche sat a little higher, but the doors were easier to close. Both cars had liftgates that were easy to reach even if you are under 5'4".
In terms of livability I liked the interior treatment of the Porsche better. However, the rubber floor mats on the Cayenne and the cheap looking and feeling covers for some of the HVAC controls violated my understated tastes. For the price, neither car has a very luxurious interior. The Porsche has more switches and gauges with a control for the locking differential and height adjustments on the center console and Porsche's usual too small to read radio controls in the dash with steering wheel satellite buttons.