This paper presents the results of an on-road evaluation of in-cylinder ceramic thermal barrier coating GPX″-4M and turbocharger clearance control coating. Engelhard Corporation carried out the testing as a part of a pre-production product development and evaluation process.Contained in the paper are the results of a three-year long experiment conducted on an Engelhard's truck. Discussed in the paper are in-service performance and durability of Engelhard's coating.The experimental fuel usage data underwent substantial statistical treatment and analysis. In combination with the unique test conditions this allowed credible conclusions regarding the truck fuel economy. It was clearly demonstrated that the truck equipped with in-cylinder GPX coated components used 1.4% less fuel than a standard truck for the same amount of work performed over a 16-month period. This fuel saving is associated with the engine rebuild. For that same period and same amount of work, the GPX coated truck having clearance control coating on its turbocharger yielded a 2.1% reduction of fuel consumption.A post experiment analysis of the coating conditions demonstrated good long-term durability of these products.