Until June I had a 4 door 98 Accord EX-L. Honda spec spark plugs were NGK P/N ZFR5F-11, and they were about $3 each.

Now I have a 2 door 00 Accord EX-L. The engines (and engine compartments) look IDENTICAL, but according to my dealership (and the diagrams on Majestic Honda's online parts diagrams) this car takes spark plug NGK P/N PZR5F-11, which are $13 each (!).

What is different about these spark plugs? It's the same engine, separated by only 2 model years.

 

The expensive plugs are platinum.

The interval to change spark plugs should be much longer, since platinum electrodes last longer.