Four-time series champion Sebastien Bourdais will drive the No. 18 Team SealMaster – Dale Coyne Racing w/ Vasser – Sullivan Honda/Dallara/Firestone entry at the 2018 Verizon IndyCar Series season opening Firestone Grand Prix of St. Petersburg. Bourdais, who is contesting his 13th year of IndyCar competition, is coming off a dramatic 2017 IndyCar season. He…