My wife was driving our '05 this weekend. She had the cruise set to 60 and we had the A/C on. She said that all of a sudden the car accelerated up to 70 or so before she put the brakes on. What would cause this? Have others had this? Thanks, Scott

 

Driver error.

That's what the investigators found in all those Toyota "Unintended Accelerations" from last year:
Toyota sudden acceleration report finds no electronic flaws - Feb. 8, 2011
Toyota's acceleration problem: Thousands of bad drivers? - The Week

But it probably couldn't hurt having the electronic throttle on your XG looked at.

 

For what its worth, my 2005 XG350L 6 Cyl also has a variation of sudden rapid acceleration. In my case, on sporadic occasions, the vehicle when first started and put in drive, will suddenly gallop forward in a series of jerks. Ukn what cause, dealer says no indication in code check??? Problem will go away in a minute or so. Can be halted by shifting to neutral and back to drive

 

First, you can't put the car into drive unless your foot is on the brake. So if your car is accelerating when going into drive, then it's a driver error. The problem goes away by putting your foot on the brake.

 

Thankfully our car hasn't done this again. The other night while driving along the radio CD player did come on and then the radio did, too. I'm beginning to think there is an electrical issue here somewhere.