Is it permissible for a Muslim residing in Canada, who works long hours and travels between clients, to perform prayers in the car, either in congregation or individually? And is it permissible for him to perform tayammum instead of wudu due to the lack of a suitable place or water?

A Muslim is not permitted to perform the obligatory prayer in a car for work, because the entire earth is a masjid. Likewise, it is not permissible to perform tayammum when water is available and one is able to use it. One must be careful not to be negligent in prayer and its purification.