Edit: Wanted to add that an auto plant doesn't count as manufacturing in my eyes as the raw resources are sent elsewhere to be turned into a widget and then shipped back. The widgets are then assembled. This is designed in the USA, made in China and assembled in Canada. They don't need to be here to assemble other than legislative agreements.
Oh really.
I work with Tier 1 auto parts manufacturers and the suppliers to those manufacturers. LOTS of them.
Ever hear of Magna? Number one auto parts manufacturer in the world. Based in Canada. While they do have many worldwide plants (near the assembly plants that they build parts for), they have a lot of plants right here in the Toronto area.
As you drive thru Milton on the 401, there is a large green building on the south side. They make all sorts of automotive structural parts in there. Subframes, engine cradles, axles, etc. Just off in the distance to the south is another large white building. From there, come the entire welded bodyside assemblies used in a number of cars you might have heard of. Camaro. Chrysler 300. Dodge Challenger. That plant has some HUGE stamping presses in it.
There is a Canadian company that makes belt tensioners and pulleys. Every VW diesel engine sold worldwide has a timing belt tensioner that they built. I've worked on about three generations of the line that assembles those. That company does have divisions in Europe and China ... and the production equipment in those plants was built right here.
A lot of automated welding lines for automotive bodyshells worldwide comes from a couple of different companies that are based in Canada. If you drive a late model Mercedes or BMW SUV, a Canadian company built the automation equipment that put together your doors, hood, tailgate, front fenders, and sunroof. I know that because I worked on it.
Other stuff built right here in Canada and that I've seen with my own eyes: Transmission shafts, windshields, rear windows, oil pumps, oil coolers, oil lines and hoses, coolant pumps, seat frames, seat cushions, door latches and locks, bumper reinforcement bars, instrument panel support beams, suspension links and control arms, differential housings, drive shafts, exhaust systems, and a bunch more that I've forgotten at the moment.
Honda and Toyota have assembly plants in Ontario. If you think that every part they are putting together is coming from Japan, you are mistaken. Honda has an engine plant and a stamping plant in Alliston in addition to the two final assembly plants. A lot of the parts are made locally.
While there is no "Canadian car" with a nameplate we can call our own, there is a vehicle that we can call our own ... the CanAm Spyder. Parent company - Bombardier Recreational Products. You might have heard of them. Their corporate relative, Bombardier, also make the odd airplane and train car. If you have anything that has a Rotax engine - Bombardier Recreational Products owns Rotax (although Rotax themselves are Austrian).
If you ride the bus ... chances are, it was built in Canada. Maybe it was built by Nova Bus Industries in Quebec, or maybe it was built by New Flyer in Winnipeg.
All of these put together plus all of their suppliers and other affiliates employ untold thousands of people in Canada, and it wouldn't surprise me if the total auto / transport manufacturing sector was nearer a million.