strictly than passenger cars under the Energy Policy and Conservation Act for fuel economy, and the Clean Air Act for emissions. However, from 2004 onwards, the United States Environmental Protection Agency (EPA) began to hold sport utility vehicles to the same tailpipe emissions standards as cars for criteria pollutants, though not greenhouse gas emissions standards as they were not set until 2010. In 2011, the CAFE regulations were changed to classify small, two-wheel drive SUVs as passenger cars. However, the licensing and traffic enforcement regulations in the United States vary from state to state, and an SUV may be classified as a car in some states but as a truck in others. For industry production statistics, SUVs are counted in the light truck product segment. In India, all SUVs are classified in the "Utility Vehicle" category per the Society of Indian Automobile Manufacturers (SIAM) definitions and carry a 27% excise tax. Those that are long, have a engine or larger, along with of ground clearance, are subject to a 30% excise duty. In Australia, SUV sales were helped by having lower import duties than passenger cars. Up until January 2010, SUVs were subject to a 5% import tariff, compared with 10% for passenger cars. Characteristics Chassis Many years after most passenger cars had transitioned to unibody construction, most SUVs continued to use a separate body-on-frame method, due to being based on the chassis from a light truck, commercial vehicle, pickup truck, or off-road vehicle. The first mass-produced unibody four-wheel drive passenger car was the Russian 1955 GAZ-M20 Pobeda M-72, which could be considered the first crossover car. The 1977 Lada Niva was the first off-road vehicle to use both a unibody construction and a coil-sprung independent front suspension. The relatively compact Niva is considered a predecessor to the crossover SUV and combines a hatchback-like passenger car body with full-time four-wheel drive, low-range gearing, and lockable center differential. Nonetheless, unibody SUVs remained rare until the 1984 Jeep Cherokee (XJ) was introduced and became a sales success. The introduction of the 1993 Jeep Grand Cherokee resulted in all Jeep SUV models using unibody construction, with many other brands following suit since the mid-1990s. Today, most SUVs in production use a unibody construction and relatively few models continue to use body-on-frame construction. Body style SUVs are typically of a two-box design similar to a station wagon. The engine compartment is in the front,