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A study was carried out in which most aspects of dimethyl-ether (DME) as an automotive fuel were critically evaluated. DME appeared to have positive characteristics from both the energy supply and security point of view as from an exhaust emissions point of view. DME can be made from a wide variety of fossil feedstock, among which natural gas and coal, and from renewable feedstock and waste. These energy sources will last longer than crude oil. A comparison was set up between DME and other regular and alternative fuels. This comparison covers engine exhaust emissions and well to wheel energy efficiency and CO2 emissions. It appeared that the exhaust emissions of DME fuelled engines are comparable to lean burn gas engines (heavy-duty) or otto engines with three-way catalyst (light-duty). With respect to well to wheel CO2 emission DME is rated equal to the diesel engine. Compared to natural gas DME measures from about equal (heavy-duty) to about 10% better (light-duty).

PSA, Renault, Gaz de France and TNO carried out a joint research programme with the aim to develop a CNG vehicle based on a Citroën BX 19 GTI. In order to make optimal use of CNG a optimized engine concept (increased compression ratio) was adopted. The paper describes the engine testbed work, the vehicle body modifications and the initial vehicle testing. By increasing the compression ratio from 9.3:1 to 11.5:1 the power loss of the engine when running on CNG could be limited to approx. 16%. When running on petrol a similar power loss was observed. Emissions complied with the 91/441/EEC regulation (CO: 18.9%; HC + NOx = 53.6%). Software developed by TNO specifically for this purpose enabled TNO the make use of only one control unit (EFI-4 of Delco Electronics Inc.) to perform engine management functions for both fuels. A good driving range is obtained with a minimum loss of boot space.