Development of a Dedicated CNG Compact Car

The use of compressed natural gas (CNG) as a fuel for small vehicles presents challenges associated with the vehicle cost, system packaging, and vehicle range. The University of Tennessee with primary support from the Saturn Corporation has adapted a Saturn SL1 to dedicated CNG operation with the objective being to do so with a minimal impact on the production of the base vehicle.

The adapted vehicle meets the California ULEV emission values at low mileage, achieves a gasoline-equivalent fuel economy of 21 km per liter (49 miles per gallon) at a steady speed of 90 km/hr (55 miles per hour), and has a range (at 90 km/hr) of over 400 km (240 miles) when fueled with an initial tank fill of 24.8 MPa (3600 psig). As expected, wide-open throttle performance of the adapted vehicle was degraded from the gasoline baseline vehicle.

The vehicle design features are compared with two similar pre-production vehicles that have been described in the literature.