There are exceptions to this, however. Some vehicles, such as the 1992 and 1993 Fox-body Mustangs, do use such as a system even though they have multi-port fuel injection, presumably to help the air-fuel mixture burn at the proper rate in cold weather, as even though the fuel has finely atomized, it has not properly vaporized, and therefore flame propagation will be otherwise slower. These vehicles have a MAF sensor, Air Temperature sensor, and when equipped with the 2.3L 4-cylinder, two spark-plugs per cylinder. This combination ensures the air is just warm enough to vaporize the droplets and does very noticeably improve performance and emissions at the same time in cold, northern winter weather.