In older vehicles a single (large) coil would serve all the spark plugs via the ignition distributor. In later models - 1998 onwards, many of the vehicles such as Mercedes and BMW had multiple smaller ignition coils one per spark plug or one per two spark plugs - two coils in a four-cylinder engine, or three coils in a six-cylinder engine. The single large ignition coil puts out about 20 kV, and the multiple smaller ignition coils put out about 15 kV. These coils may be remotely mounted or they may be placed on top of the spark plug. Where ignition coils are individually applied per cylinder, they may all be contained in a single molded block with multiple high-tension terminals. This is commonly called a coil-pack - often installed in the later Volkswagen and Saab models. A bad coil pack may cause a slight or not so slight misfire, bad fuel economy, loss in power.