The changes include a 1.6L turbo four for the Verano and GM's eAssist for the crossovers.

A set of leaked GM VIN documents - the same files that suggest the Chevrolet Camaro may soon receive the Corvette's 7.0L LS7 V8 as an option - have revealed that several powertrain changes are likely in store for the Buick Verano and Chevrolet Equinox/ GMC Terrain siblings.

In the VIN document for the 2014 Buick Verano, there's no mention of the current 2.4L inline-four base motor. In its place is listed a turbocharged and direct-injected 1.6L four with variable valve timing, which could become the new entry-level engine for Buick's compact premium sedan.

As no further details are included in the document, it's unclear whether the mill is all-new, a version of an existing world-market engine or - as Motor Trend suggests - an enlarged version of the turbo 1.4L used in the Chevrolet Sonic and upcoming Buick Encore.

The documents also reveal that GM's mild-hybrid eAssist powertrain may find its way into the 2014 Chevrolet Equinox and 2014 GMC Terrain as an efficiency-boosting option. In its current applications, the powertrain consists of an 182-horsepower 2.4L four and an electric motor that provides 15 additional ponies.

GM has yet to officially confirm any of the details listed in the leaked VIN documents, but we'll keep you updated as more information becomes available.