A fleet of big, shiny Cadillacs roamed Los Angeles this week, but unlike any other week in L.A., these cars were being shaken out by journalists on Mulholland Drive, the insanely twisty road where big Caddys once feared to tread.

I am not here to talk about performance. My colleague Kirk Bell will let you know how the new 2013 XTS performed on Monday. Me, I'm talking about something else. Yesterday I covered how Cadillac's pricing and sizing strategies don't make sense. But today I'm here to report how it felt to use the car's vibrating seat alerts and new Cue infotainment system in real-life situations -- or whatever passes for "real" in Beverly Hills.


Is that my cell phone buzzing, or the seat?

Cadillac has a good idea here. Instead of annoying the driver with flashing lights and buzzing sounds from various active safety systems, it sends all those warnings to his back and rear end. The seat cushion vibrates, on either the left or right side, depending where you're drifting in the lane.

It'll also vibrate on either shoulder if it detects a vehicle in the blind spot, which I wasn't foolish enough to try. Both sides and portions of the seat vibrate at once -- along with a flashing red warning on the heads-up display -- if the forward collision sensor thinks you're about to crash into the car ahead. That happened twice. Hey, it's L.A.

Overall, it's pretty effective, though on winding roads in a wide Cadillac, it's rather easy to provoke the alerts. Thankfully, for those times and others like it, the system can be switched off with a button on the dash.

Ah, but there are no buttons

That's right. Only the icons on the steering wheel, the door switches and a few other controls such as the ignition are physical buttons. The entire center stack, including the air-conditioning controls in the rear, are touch-capacitive, just like your iPad. The iPad inspired the car's design team, and one even comes with the car, just like what Hyundai did with the Equus during its first model year.

The center LCD display is clever. It uses proximity sensors to display menu options when your hand waves near, and clears them when you're done. It reduces screen clutter, which I like. Also, the screen is "haptic," meaning it sends a small, vibrating "bump" to your finger when you touch an icon (Blackberry users know this idea well). I like that, too. You can swipe menu icons and drag them around like on an iPad, plus you can pinch your fingers to zoom the map -- though it responded rather slowly. Overall, though, Cue felt pretty quick and easy.

The touch-capacitive dash is another story. See those silver trim pieces that look like you should touch them? Don't. They're just finger guides. The actual sensors are above them, which is confusing and frustrating. They're also slow to respond to repeated inputs, like adjusting the cooled seat or the fan speed, unless you're deliberate with your pace and timing. Who wants to think about how you touch a control, especially while driving? Lincoln already came out with this system and it's no different. It's like tapping a plastic post and wondering if some magic will happen. You also feel kind of dumb getting it wrong, which tends to happen when you're paying attention to the road.

This feature needs to die. If you're in the older 50-plus demographic who will buy a big Cadillac sedan -- and you use an iPad -- please prove me wrong when this car goes on sale.