I never renewed my subscription after the trial ended. I use Google traffic on my smartphone instead. I already pay for a data plan, so it comes for 'free.' Traffic updates are far more real time, and there's a lot more road coverage. Kind of a shame it can't be integrated into the Nav unit in lieu of XM/Sirius.
For that matter, I use Pandora instead of XM Radio also. I'm running high quality audio mode, and it sounds better than XM/Sirius for whatever reason. I'm on the road for at least 3hrs a day. That works out to be about 500MB/week.
I let my Sirius subscription expire in my Sync unit in my Ford truck as well. Fuel prices on that Travel Link thing were never less than 1-2 days old. Useless. I use GasBuddy on my phone instead.
The best part is, I pay for one data plan on my phone and it goes with me regardless of the number of cars I drive. No need to mess with multicar subscription rates.