A coworker and I both have to go testify in a case, with the courthouse being around 4-5 hours of driving away depending on the traffic.  My coworker said she isn't a good driver and doesn't like driving long distances, and said she would come along with me while I drive.  Not only do I not particularly want to spend 4-5 hours in a car with her, but I also had plans on making the most of my trip and visiting the city and grabbing a few drinks without being responsible for someone else as well.  

Yesterday when she first asked I kind of tried to laugh off her suggestion and said I'd think about it, even though I had pretty much made up my mind that I wanted to drive solo.  Today I come into work to a piece of cake on my desk she had gotten with a "thank you for driving me" note, with a few others in the office laughing and thinking I'd apparently be thankful for her "gift."  I again tried to laugh it off and thanked her for the cake but that I still wanted to go alone, and she got upset as she left work for the day.  The other ladies in the office also seemed taken back and that I was being rude.  

AITA here for not allowing her to carpool along with me?  I wouldn't really want to drive her anyways, but the way she kind of  just jumped in and tried to impose to grab a drive without asking me if I was okay with it, or if I had any other plans for the day, also made me want to say no.  A few others at work think I am a jerk for not driving her, but I don't think there's anything wrong with my choice.  What do y'all think?  