The EPA's getting quite a few mentions on TTAC today, but it's not because of the agency's planned rollback of corporate average fuel economy standards. No, it's because of odd fuel economy rollbacks seen among 2019 Chevrolet models.

We told you earlier about the yet-unexplained drop in city and combined fuel economy for the 2019 Chevrolet Colorado and GMC Canyon diesels. Now you can add the 2019 Chevrolet Camaroto the list of models with missing MPGs. It seems that in one area of performance, 10 speeds isn't better.

First noticed by Motor Trend, the refreshed model doesn't gain newfound fuel economy with the addition of a multi-cog automatic. In fact, it loses some. For 2019, V8-powered SS models trade the previous eight-speed automatic for a smooth 10-speed unit. Given that a greater number of cogs means a wider ratio spread and thus greater efficiency, you'd think the 2018 SS would go a little further between fill-ups.

Instead, the automatic-equipped 2019 Camaro SS keeps its 27 mpg and 20 mpg highway and combined ratings, but sees its city rating fall from 17 mpg to 16 mpg. Understandable, you say. After all, the GM 10-speed sees lower gearing in around-town gears - a first-gear ratio of 4.70:1 replaces the eight-speed's 4.56:1 first gear, for example. You have to get up to seventh gear in the 10-speed to match the ratio of the eight-speed's sixth gear, and, while the new tranny moves up through the gears at a quicker pace, it's not enough to offset those lower ratios.

Fine, but that doesn't explain the MPG discrepancies between the 2018 and 2019 Camaro V6 equipped with either an eight-speed auto or six-speed manual. The powertrains are carryovers for the new model year. With the automatic V6 model, city and highway economy stay at 19 mpg and 29 mpg, respectively, but combined economy drops from 23 mpg to 22 mpg.

With the manual V6, city and combined fuel economy remains at 16 mpg and 20 mpg, but highway economy falls 1 mpg to 27 mpg. Maybe the Camaro's new face has something to do with this, but GM claims the model's reworked visage is slipperier than before.

If the EPA tweaked its testing for the 2019 model year, we weren't informed. Pouring cold water on that theory is the fact that the automatic and stick-shift 2.0-liter turbo models retain their previous EPA ratings for 2019. No change at all.

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