here's some info. platinum plugs fire at a lower voltage. this helps out of tune cars with weak ignition systems to maintain firing. copper plugs are hotter plugs that don't fire until more voltage has built up. this produces a more powerful spark, if the ignition system is up to it.

i tried bosch platinum 4 plus plugs in my 190e 2.3L 16v and wasn't too impressed. when my engine started missing about 6k miles later i put in four new platinum 4 plus plugs which worked fine for a few days. i then added jacobs 8.5mm wires and bosch super copper plugs overgapped .05" and this improved throttle response and acceleration noticeably. of course it's not like i got 10 BHP from plugs are wires but there was a small difference. a week later i replaced my rotor and distrubutor cap. again, a noticeable improvement. so if you're thinking about igntion stuff, for under $100 you can replace your rotor, cap, wires, and plugs and get your ignition running like it just came off the showroom floor, or even a little better with the beefed up wires and increased gap.

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dew
86' 190e 2.3L 16v