Sorry! I forgot about that question! Yep, the pipe inside the front grille is just a vacuum tank. I work it out at around 2 litres capacity. If I were to do it again I'd make it 5 litres so I could do a couple of crazy emergency stops without the thing emptying so quickly.
Unfortunately I lost the soft copy of the "EV info card" when I wiped my PC some months ago. It just told the viewer the basic specs and let them make their own mind up. Voltage, top speed, cost to run etc. I had the sheets laminated in case it rained. You could do the same but at the same time offer cards for people to take so they'll remember to follow up next time they empty out their wallets!