With its clusters of used-car dealerships along Lincoln Highway and Route 13 in Lower Bucks, Doylestown and Quakertown, Bucks County has passed Pennsylvania’s first county-level used-car lemon law. The new law, which takes effect Jan. 1, offers minimum guarantees to consumers who purchase used vehicles over seven model years old and that have less than 100,000 miles. Dealers who sell vehicles with broken engine blocks or bent frames without disclosing it to the buyer, or sell vehicles that can’t pass state inspections, will be in violation of the new regulations, officials said. Violators can …