Each F40PH has a 1500 gallon fuel tank (2 locomotives per train) let's say it burns 170 gallons per hour per locomotive for a 4 day journey (96 hours) 32k gallons for the whole train to go from Toronto to Vancouver. But the train can carry 150 people and more if you count the people getting on and off (806L per person).
If you were to do that in your car at 43mpg (9.1l/100km) to 4500km (2800 miles) which will require 235L of fuel to get there (one person).
This is probably not an accurate representation however what to take into consideration is that the train is running regardless of if you drive so if you take the train instead of driving you save the planet by not burning an additional 235L of fuel x 150 people who did the same thing. Which is 35kL.
Your example should tell you why nobody takes the train to get across the country. The real comparison is not against a solo driver which is exceptionally rare. It's against an airline passenger or multiple passengers in a car (with two pax, fuel consumption per passenger is halved). And they most definitely aren't doing it solely for transportation. How do I know this? Because I see it all the time in the military. Anybody driving long distances is usually doing so to move their car, often at substantial expense to themselves, not because it's the cheapest form of transportation (which we are mandated to use). They usually do it to have a car to use locally. Nobody is driving 3 days from Winnipeg to Trenton for a 6 week course because it's the cheapest way to get there. When the carbon tax triples in 2030, this choice will be even more expensive for anybody not driving an EV.
On topic, the way to look at this math is to use the metric of litres per passenger-km or gallons per passenger-mile. Use that and you'll quickly realize how inefficient long haul rail is. Airbus claims that the A220 at high density on medium-long haul is down to 2L/100 pax-km. Even if we were to discount their claims because of lower density and less than full load factors, even at double the fuel consumption (4L/100 pax-km), long haul diesel rail would find it difficult to compete. Moving bedrooms and kitchens thousands of kilometres over days with diesel power is simply inefficient. That's just physics. The only way long haul passenger rail can ever beat air travel or driving is with full electrification. It's what makes sleepers competitive in Europe. We will never have this in Canada.
So, like I said, unless they can find a fuel substitute that avoids the escalating carbon tax, long haul diesel travel will keep increasing in price, driving even more discretionary long haul passenger rail travelers to choose air or road. VIA long haul, if it survives, is very likely to be cut down to bare minimum for what the remote communities en route need.
What you should be worried about isn't VIA long haul. It's the same thing happening to Corridor services in 2040, when most people have EVs and the airlines are deploying electric short haul and sustainable aviation furls, as the carbon tax goes to over $200/tonne.
