Not sure if anyone else has had this problem, but wanted to share - just in case. Over the last couple years or so I installed E3 Spark plugs in all my vehicles. To my amazement they were OUTSTANDING. Better gas mileage, smoother ride, etc. instantly. However after about 15K miles in my 2006 X-Type, it started coughing and sputtering very badly. Unfortunately NO Check Engine (CE) light, so no codes to help me (We checked). After days of trial and error; tried changing the fuel filter, injection cleaners, octane boosters, trying different gas stations, etc., all to no avail. Finally one day the coughing got so bad, the CE light came on. The code showed Cyl 1 misfire. So I did the dreaded deed, and replaced my spark plugs. BAM – Coughing gone.

Not sure if others have similar problems but for me the E3’s were not a good fit for my X-type. The other cars are still doing great. Just something to consider if changing Spark Plugs.