profile increases wind resistance and greater mass require heavier suspensions and larger drivetrains, which both contribute to increased vehicle weight. Some SUVs come with tires designed for off-road traction rather than low rolling resistance. Fuel economy factors include: High masses (compared to the average load) causing high energy demand in transitional operation (in the cities) where stands for power, for the vehicle mass, for acceleration and for the vehicle velocity. High cross-sectional area causing very high drag losses especially when driven at high speed where stands for the power, for the cross-sectional area of the vehicle, for the density of the air and for the relative velocity of the air (incl. wind). High rolling resistance due to all-terrain tires (even worse if low pressure is needed offroad) and high vehicle mass driving the rolling resistance where stands for the rolling resistance factor and for the vehicle mass. Average data for vehicle types sold in the US: Drag resistance (assuming the same drag coefficient which is not a safe assumption) for SUVs may be 30% higher and the acceleration force has to be 35% larger for the same acceleration, which again is not a safe assumption, than family sedans if we use the figures from the above table. Pollution Because SUVs tend to use more fuel (mile for mile) than cars with the same engine type, they generate higher volumes of pollutants (particularly carbon dioxide) into the atmosphere. This has been confirmed by LCA (Life Cycle Assessment) studies, which quantify the environmental impacts of products such as cars, often from the time they are produced until they are recycled. One LCA study which took into account the production of greenhouse gases, carcinogens, and waste production found that exclusive cars, sports cars and SUVs were "characterized by a poor environmental performance." Another study found that family size internal combustion vehicles still produced fewer emissions than a hybrid SUV. Various eco-activist groups, such as the Earth Liberation Front or Les Dégonflés have targeted SUV dealerships and privately owned SUVs due to concern over increased fuel usage. In the US, light trucks and SUVs are held to a less-strict pollution control standard than passenger cars. In response to the perception that a growing share of fuel consumption and emissions are attributable to these vehicles, the Environmental Protection Agency ruled that by the model year 2009, emissions from all light trucks and passenger cars will