Having spent over 20 years in the industry, it never ceases to amaze me that people don't go electric whenever possible in the application is indoor. The initial expense of the vehicle, the battery and charger, etc., is expensive, but electrics do not have emissions and over the normal life, use less than half the parts and service of an internal combustion vehicle. Also, it's not so much what the vehicle effluent is to the indoor environment as much as it is the ventilation of the indoor environment. The more closed, the less acceptable an IC vehicle is. Personally, with all the continuing 'green' emphasis worldwide, I'd recommend starting to get into electrics wherever possible and learn how to optomize the battery life.