How many Canadian tourists take a trip to visit Selfridge Air Force base? (The example the senator gave)
I agree that passive surveillance is a more likely threat, but the Senator claimed the threat was someone taking a deliberate trip to observe the airbase using the car's sensors.
Plus, it presumably wouldn't be very hard for the hypothetical MSS undercover operatives to set up a scheme installing or hijacking the very same surveillance devices in a non-CN vehicle. From something as simple as just renting and secretly modifying US cars themselves (thus slowly "seeding" the pool in an area of interest), to outright setting up their own or acquiring an existing car rental or a car repair shop servicing a rental company via an oblique network of investment firms.
If they
really wanted to pull something like this, restrictions on obviously Chinese products are probably the easiest problem to solve for whoever would be tasked with a mission like this.