Question: The Ford Explorer and the Mercury Mountaineer are very similar vehicles. What year did the Ford Explorer start being produced?

Related documents: [0]  [DOC] The Mercury Mountaineer was a mid-size luxury sport utility vehicle (SUV) that was sold by Mercury from 1997 until 2010. Sharing many of its features with the Ford Explorer, the vehicles were virtually identical in terms of hardware. Externally, they were styled somewhat differently, and the Mountaineer was positioned with a more upscale interior, with the Mountaineer's MSRP coming in at $1,000–$6,000 more than the Explorer. It was last redesigned for the 2006 model year with a new frame, looking very similar to its previous model. [END] 
[1]  [DOC] The Ford Explorer is a full-size sport utility vehicle produced by the American manufacturer Ford Motor Company since 1990, based since 2010 on a crossover platform. The Ford Explorer became one of the most popular sport utility vehicles on the road. The model years 1991 through 2010 were traditional body-on-frame, mid-size SUVs. For the 2011 model year, Ford moved the Explorer to a more modern unibody, full-size crossover SUV platform, the same Volvo-derived platform the Ford Flex and Ford Taurus use although with significantly greater ground clearance. It is slotted between the traditional body-on-frame, full-size Ford Expedition and the mid-size CUV (Crossover Utility Vehicle) Ford Edge. Although outwardly similar, the fifth generation Explorer, Ford Edge and Ford Escape do not share platforms. The fifth generation Explorer does, however, share platforms with the Ford Flex and Lincoln MKT. [END]  
Answer: 1990
1990