The FAA has for some time been conducting tests from several potential fuel distributors in an effort to see which of the entries can best supply the general aviation fleet with an aviation fuel which does not contain unacceptable quantities of lead.
Aero-News today published an article describing the results of the first phase of testing. In it they say:
Fuel formulations from Shell and Swift Fuels were selected for Phase 2 engine and aircraft testing. Test data will help the companies obtain an ASTM International Production Specification for their fuels and allow the FAA to authorize the existing GA fleet to use the unleaded replacement fuels. The testing will begin this summer and conclude in 2018.