alterations were made on the preliminary models: tapering the rear waistline and rear side windows by about 50 mm compared to earlier mockups gave about 0,035 Cd improvement, while another 0,035 improvement was reached by altering panel lines, transition points, integrated front spoiler in front of the tires, engine shield and a panel connecting the fuel tank and the lower edge of the rear bumper. The Calibra remained the most aerodynamic mass production car for the next ten years, until the Honda Insight was launched in November 1999, with a Cd of 0.25. All later 16V, V6, 4x4 and turbo models had a worse Cd of 0.29, due to changes in cooling system, underbody, use of spoked wheels and glass detail. Commercial life During its lifetime, the Calibra was much more popular in Europe, and outsold its nearest rival, the Ford Probe, which was considered to be underpowered, and very American for most European drivers. Sales of the Vauxhall-badged versions for the UK market commenced in June 1990, with hopes of selling of up to 15,000 examples per year. However, this sales target was never achieved. In July 1990, after General Motors bought a stake in Saab, it was reported the Calibra would be badged as a Saab in the United States, but these plans did not materialise. There were also plans for a cabriolet version to be produced, but these too failed to materialise. In the summer of 1994, the Calibra received a light facelift. Most noticeably, the manufacturer badge migrated from its place atop the leading edge of the bonnet into the front grille. Equipment and safety have been developed. Throughout the production run, several special models were launched. In the United Kingdom, this began with the 'Tickford' conversion in October 1991, however, only 26 Calibras were ever converted. This was followed by Vauxhall's own Special Edition range the SE1 in 1993, and ran through to the SE9 in 1997. These limited run editions had often unique aspects. For example, solar yellow paint on the SE2, or "Icelandic" blue on the SE6. Neither colours were found on any other Calibra in the UK. There was also a Keke Rosberg edition first only available in white, in celebration of the Calibra's success in the German Touring Car Championship at the time. In other parts of Europe, special models included the "DTM" edition, the "Cliff" edition, the "Colour" edition, "Last"