It appears that Chevy isn't following its own precedent as the Chevrolet Volt plug-in hybrid enters its third model year.

In the past, the Volt received a battery upgrade every other year that provided it with increasingly more electric range—but that's not the case for the largely unchanged 2018 Volt. 

The first information comes from a dealership guide found by CarsDirect, which reveals only a handful of minor changes to the bowtie brand's second-generation plug-in hybrid hatchback. 

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According to that ordering guide, the base LT model sees the most changes, relatively.

It gets a beefed-up audio system with eight speakers and a newly available Driver Confidence Package that includes blind-zone monitors, rear cross-traffic alert, and rear park assist.

But the Volt LT loses its previously standard leather-wrapped steering wheel in favor of a urethane unit.

2017 Chevrolet Volt

2017 Chevrolet Volt

To get a leather wheel requires purchase of an additional Comfort Package, which cost $460 this year.

The Driver Confidence Package will be an extra-cost item and it requires that buyers select the optional leather upholstery package and the Comfort Package first. 

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An eight-speaker Bose-branded audio system remains optional for the Volt LT trim level; it's known as the UQA option.

The 2018 Volt also sees its color palette modified, too; Siren Red Tintcoat, Citron Green Metallic, Heather Gray Metallic and Pepperdust Metallic are gone.

2017 Chevrolet Volt

2017 Chevrolet Volt

In their place, Cajun Red Tintcoat, Green Mist Metallic and Satin Steel Metallic are all making their first appearance. 

The Volt's 18.4-kilowatt-hour lithium-ion battery pack carries over apparently unchanged.

That means its EPA ratings will likely stay the same as well: 53 miles of electric range, and energy efficiency of 106 MPGe, and 42 mpg combined when running on gasoline after the battery capacity is used up.

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Chevy hasn't yet announced pricing or an on-sale date for the 2018 Volt, but it's unlikely that these updates will significantly alter the 2017's $34,095 base. 

CarsDirect suggests that production of the 2018 Volt will begin in July, meaning the updated models should start hitting dealership lots in August.

Since the second-generation Volt, introduced for 2016, was only available in a handful of states that year, perhaps we can count 2017 and 2018 as the first two full model years—and hope for a battery upgrade for 2019?

EDITOR'S NOTE: An earlier version of this article indicated that the Bose eight-speaker sound system would be standard on the Volt LT trim level. According to Chevrolet spokesman Fred Ligouri, it should be listed as optional. We have updated the article.

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