Quoted from: http://www.issrc.org/ive/ 

The International Vehicle Emissions (IVE) Model is a computer model designed to estimate emissions from motor vehicles. The model is intended to help cities and regions develop emissions estimates to:

• Focus control strategies and transportation planning on those that are most effective;
• Predict how different strategies will effect local emissions; and
• Measure progress in reducing emissions over time.

The model makes estimates of local air pollutants (criteria pollutants), greenhouse gas emissions, and toxic pollutants.

Why is it needed?

Emissions from vehicles in most countries, particularly developing countries, are not well understood, and the ability to make accurate emissions estimates is critical for air quality management planning. Only a few countries, such as the U.S. and Europe have developed reasonably accurate emissions projection tools, and these models are designed only for their respective regions. The U.S. and European models cannot take into account the differing technologies and conditions that exist in most developing countries. Most of these existing models do not include the full range of global warming and local toxic emissions that are needed to fully evaluate the impact of motor vehicles. The International Vehicle Emissions (IVE) Model is specifically designed to have the flexibility needed by developing nations in their efforts to address mobile source air emissions.