This question is asked very often. In days gone past, the answer was yes. But with modern day motor trade insurance, the answer is no UNLESS it is for the purpose of your motor traders business (and then we still recommend checking with your broker to ensure the appropriate level of cover is available).
Even if your policy does allow you to drive other vehicles, high performance vehicles or imported vehicles may not be covered as standard due to their additional risk level. You can easily however add this as an additional feature to your policy should you wish.