Mercedes-Benz revised and updated the W163 in 2001 for the 2002 model year. Styling updates involved the fitment of new head- and tail-lamp lenses, front and rear bumpers, new alloy wheels on most variants, the relocation of the side turn signals from the fenders to the side-view mirrors, and various interior trim changes. At the same time, the ML 430 was replaced by the 5.0-litre V8-powered ML 500 and a new 4.0-litre V8 turbodiesel ML 400 CDI became available in Europe. The following year, in 2002, Mercedes-Benz launched the ML 350 fitted with a 3.7-litre V6 engine. The ML 350 replaced the ML 320 in some markets, but supplemented it in others. The previous Popemobile was based on a W163 series ML 430 and has been in service since July 2002. Volkswagen had offered to build a new vehicle based on the Touareg, but Pope Benedict XVI opted to continue using his predecessor's Mercedes-Benz-manufactured vehicle. Second generation (W164; 2005) In 1999, development on a successor to the W163 began under the codename "W164" and spanned a period of 6 years. First design drafts have appeared in 2000 with the first production models in scale 1:4, and in 2001, three full-sized versions were prepared. By late 2001, the production design styled by Steve Mattin under Peter Pfeiffer was chosen and approved by the executive board in 2002. The design patents were filed in Germany on 10 June 2003, and in the U.S. on 25 July. Prototype testing was conducted throughout 2003 and 2004, concluding in early 2005. The redesigned M-class (chassis name W164) was introduced in April 2005 as a 2006 model after a showing at the North American International Auto Show in January. It was almost entirely new, with a more sporting, aerodynamic look—the coefficient of drag went down to 0.34 compared with the previous generation. Mercedes-Benz made the new M-Class 71 mm larger, 150 mm longer and 5 mm lower than the first model. The M-Class was named "Best New Sport Utility Vehicle" in the 2006 Canadian Car of the Year awards. Mercedes-Benz extensively publicised the US$600 million spent to update its factory and add manufacturing space for the new R-Class. According to early automotive press reports, the 2006 M-Class vehicles demonstrated vast improvements in quality. The W164 platform used for the new M-Class is shared with the new GL-Class and is a unibody type rather than the former