10 Best Spark Plugs 2025 in the United States

Good spark plugs are essential for your car to run efficiently. You'll see double- and single-grounded spark plugs. The double-grounded electrodes will typically last longer--if one electrode wears out, the spark plug will continue to run with the other electrode. There are also fixed-gap and adjustable-gap electrodes: having the gap between the electrodes at the optimal size for your automobile is essential for proper fuel efficiency. Also, pay attention to the "reach" of the spark plug: this is how far the spark plug can be threaded into the engine's combustion chamber, and in turn if the spark plug is achieving optimal combustion. Choose your car's spark plugs according to the car's specifications, noting what spark plug is best for it.