Yes, it is. He neglected to mention this to police initially, claiming to have remained at home. When confronted with the fact that his phone pinged towers on the Calder, he suddenly remembers taking it for a drive & claims to have done so to address a problem with the fuel gauge, which apparently rectified itself after he went over a bump in the road. No doubt he would claim to have left the keys to his own car at home for Karen to drive to work.
He claimed to leave home in her car at 10:30am, and have returned a couple of hours later.