The conventional spark plug (or plugs) of a spark-fired gasoline engine are removed and replaced with a high-power spark plug (or plugs) capable of delivering very high power (e.g., one megawatt) over a relatively-narrow time interval (e.g., 20 nanoseconds). Next, the gasoline is replaced with a readily-available non-volatile fuel (e.g., JP-8). The gasoline—and its transportation, storage, handling and/or use—is eliminated altogether, thereby removing a strategic and tactical threat from enemy and terrorist forces who otherwise would be targeting the gasoline tanks or transports. Additionally, or alternatively, the fuel in the line (or the fuel injector) may be heated to start a cold engine or under cold ambient temperatures. The invention is also applicable to consumer products (e.g., lawnmowers) where the extra expense of occasional use is a tradeoff for safety and convenience.