Given (1) the well-established propensity for mosquitoes to congregate around diesel, gasoline and propane fumes - at least our Alaskan species of the pest - AND (2) mosquitoes' of every species making use of CO2 exhalations to target their prey, I'm finding your suggestions needing more evidence. To give you the benefit of my doubt, however, I'm wondering if this is a new-vehicle phenomenon: perhaps the outgassing either of the vehicle's seating material - whether leather or the "vegan" artificial material - is something Hong Kong's mosquitoes find attractive?