Ted does raise his eyebrows at Joan when Sherlock shares that little tidbit. He wouldn't think Joan had ever stolen a car, no. Well, not without very good reason, at the very least.

"Wait, so, you were sponsored by a former car thief...?" Ted asks, confused by that part. Clearly he thinks in the term of sports teams having sponsors. For one thing, he thought Sherlock had all the money he needed.