都城嘉慕威曼都城巴士
Having already used a DAF SB220 chassis on the Delta, now as part of United Bus, Optare collaborated with DAF to design the Optare Spectra. It was based on the modified design of the MCW Metrobus purchased by Optare, and combined parts from it and the SB220 to form a new double deck chassis, designated DB250, with Optare bodywork called Spectra. Due to the United bus relationship and joint design, the Spectra was built exclusively on DB250 chassis. As well as having a striking front end, the Spectra was also recognisable for having no rear window. Introduced in 1990 it was described as a "partly low-floor double-decker". Despite the association with DAF, in 1991 Optare also launched a conventional height midibus in on the MAN 11.180 chassis, the Vecta.