I don't know about speed, but I have a CRV, and I disappear into the crowd, with a higher vantage point and more room than a Camry or Corolla, which are also very good melt-into-the-crowd type vehicles as well.
How much speed do you need? Almost anything can keep up with someone staying near the speed limit. If they're driving a Ferrari, you lose in anything that looks normal and doesn't attract attention. If you want a little better performance, any import engine can be modified pretty nicely for some money to get you the responsiveness you want.