I think filling 4 cars or more on one train is quite reasonable especially at the $25 price point (it's half what Megabus is charging). Many trains that VIA operating are already longer than that. It's also more possible to have a higher load factor if the trains operate nonstop, since seats are occupied for the entire trip rather than left empty if a passenger disembarks at an intermediate statin.
So how exactly is that supposed to work? Adding HEP1/2 cars at the end of a Siemens trainset?
First, you’d have to check with Siemens first, since the contract includes a warranty and all maintenance (incl. parts, IIRC), they will define what is a permittable use and what isn’t. (The regulator might also have a word)
Second, you now have a train which is different to all the other trains, which undermines the operational flexibility and fleet & product standardization the fleet renewal was supposed to achieve.
Third, you won’t be able to double-berth your monster train at Union Station, which means that it will annoy Metrolinx.
Fourth, you’ll need to do a round-trip with the same consist and crew, to minimize your costs, which reduces operational flexibility further, especially in the case of massive delays.
Fifth, the need to turn the train will cause you an otherwise entirely unnecessary extra trip to TMC (which Metrolinx won’t like), where the Siemens trainset must be shunted from one end of your HEP cars to the other.
I'm more worried about how much ridership a lower cost will induce vs cannibalize from existing trains. It's hard to figure that out without actually running the trains and testing the waters (
however half of Ouigos's ridership comes from modal shift or induced demand). I'm not sure there's a more opportune time than right after delivery of the new Venture trains is complete. It may also be a good opportunity for VIA to field test ways of reducing direct operating costs per km on the rest of its services.
Let’s assume that only a quarter of passengers is demand diverted from existing trains and that they currently pay $50 (which is unrealistically low, given that VIA’s lowest Escape bucket fare is $49, IIRC). This means that three-quarters of passengers generate a net revenue of $25 (i.e. the ticket fare), whereas the final quarter of passengers makes you loose $25 (i.e. $25 ticket fare minus the $50 they would have paid otherwise). Now your average net revenue halves to $12.50 (75% * $25 + 25% * -$25 = $18.75 - $6.25) and your break-even point doubles to 540 passengers (i.e. 8 car loads, meaning you’d now have at least 13 cars hauled by a single locomotive!). Oops!
I think one thing that separates the corporate culture between Metrolinx and VIA is their willingness to experiment. I find that VIA is far more cautious and slow with what they do. Whereas Metrolinx is more willing to throw stuff at the wall and see what sticks (Metrolinx runs circles around VIA when it comes to pilot projects).
I would assume that this attitude can be better explained with the attitude towards innovation or taking risks of VIA’s and Metrolinx’ political masters than of their respective management boards. From my personal experience, it is almost impossible to exaggerate the “why make a decision if you can just ask another question without being in any way interested in the answer” and “hide your ass” mentality at TC…