App icon for General Motors Apps

General Motors Apps

March 4, 2024
myChevrolet preview
myGMC preview
myBuick preview
myCadillac preview
Previews of General Motors iOS apps

General Motors (GM) has four unique mobile apps for their car brands with similar install sizes:

  • myBuick - 449.7 MB
  • myCadillac - 464.8 MB
  • myChevrolet - 535.0 MB
  • myGMC - 492.6 MB

Let's look under the hood to see what they share and how they can improve.


If we look at Emerge's X-Ray for each GM iOS app, we can see they are nearly identical, with small exceptions in theming/assets. Let's take a closer look.

myCadillac X-Ray

myCadillac X-Ray

myBuick X-Ray

myBuick X-Ray

myChevrolet X-Ray

myChevrolet X-Ray

myGMC X-Ray

myGMC X-Ray

The X-Rays show the same dynamic frameworks (heresdk.framework, TardisHybridContainer.framework, instabug.framework, etc.), localized strings, Watch app, and odd.bundle. The largest similarity is the TardisHybridContainer.framework, a dynamically linked framework using React Native in all four apps.

X-Ray of Tardis framework
X-Ray of Tardis framework
We've seen the pattern of using React Native in other apps, like Shopify with their ShopifyReactNative.framework.
X-Ray of Shopify iOS app
X-Ray of Shopify iOS app

While Shopify's framework doesn't appear to have significant size bloat, the TardisHybridContainer.framework is over 200 MB and can benefit from a number of low-hanging optimizations. The impact of these changes is magnified, considering it is used in all GM apps. Emerge’s insights show 170-230 MB of bloat for each app, largely from the Tardis framework.

Potential Optimizations

Scaled images outside of asset catalogs

Scaled images enable App Thinning to only include the image required for a user's device. This only works if the scaled images are in an asset catalog.

The Tardis framework ships most of its scaled images ([email protected]) outside of asset catalog. This means that something like illustrationdigitalkey3.png, [email protected], [email protected] are all being downloaded to a user's device, even though they'll only ever access one of those image files.

Examples of scaled images included in TardisHybridContainer.framework
Examples of scaled images included in TardisHybridContainer.framework
illustrationDigitalKey1 image
illustrationDigitalKey1 image

GM could shave 40+ MB from each app if it moved its scaled images into an asset catalog.

myChevrolet could cut ~8% from total app size by putting scaled images in an asset catalog

It's important to note that React Native (RN) does offer some scaled image functionality. When you use the "@2x" and "@3x" suffixes in RN, you denote specific files for specific screen densities, similar to how it works on iOS. The RN bundler will then "bundle and serve the image corresponding to a device's screen density" (docs). However, unlike native asset catalogs, the unused images will still be downloaded to a user's device, despite never being used. This is why we commonly see "scaled image" bloat in RN apps like the GM apps, Discover, or Dave.

In the case of the TardisHybridContainer, the framework is, as the name suggests, hybrid. Tardis is already using an asset catalog, so the optimal strategy is to move all scaled images to its asset catalog. For hybrid apps, RN lets you use images in a native asset catalog (docs).

Asset catalog in TardisHybridContainer
Asset catalog in TardisHybridContainer

To summarize, if you're building a native app, there is no reason not to use an asset catalog. If you're building a hybrid app, you can get the best of both worlds and use asset catalogs to avoid size bloat. If your app is solely RN, then the bundler will handle delivering the correct scaled image, but unused scaled images will still be included as bloat. Here's a list of notable apps with a large amount of app size from scaled images outside an asset catalog.

AppScaled Image Savings (MB)
Fitness App165.9 MB
TD Bank (US)68.6 MB
Wix Owner54.6 MB
Eight Sleep50.2 MB
Auntie Anne's49.3 MB
Evernote48.3 MB
Dave43.5 MB
Rocket Money43.3 MB
myGMC42.8 MB
Spaces by Wix41.8 MB
myChevrolet41.5 MB
myBuick38.1 MB
myCadillac33.7 MB
Wells Fargo26.7 MB
Discover23.2 MB
Dominos22.5 MB
Discord21.9 MB
Chime21.1 MB

Duplicate and unnecessary files


The above is a 1.2 MB LaunchScreen-myBuick.png image in the Tardis Framework's asset catalog. We found this myBuick image in the myChevrolet app. Within each app, GM is shipping assets for all four car brands, both in the Tardis Framework and in the main app asset catalog. This is happening in both the Tardis framework and the asset catalog in the main app target.

While there might be a reason to have images of the other car brands in each app, the apps have significant resource duplication in the Tardis framework. Identical directories like "energy-assistant/etc/images" | "energy-assistant-exp/etc/images" and "energy-assistant/etc/fonts" | "energy-assistant-exp/etc/fonts" are duplicated within the Tardis framework. Each app has 30+ MB of duplicate resources, much of it already in a dynamic framework.

Duplicate fonts in TardisHybridContainer.framework of myCadillac
Duplicate fonts in TardisHybridContainer.framework of myCadillac

Other optimizations

Outside of TardisHybridContainer.framework, all GM apps have significant potential for image optimization savings and minifying localized strings (stripping strings of extra comments and/or whitespace). A significant 10%-13% size decrease can be achieved in each app by a basic compression for images in odd.bundle (which seems to contain large vehicle-specific assets) and TardisHybridContainer.framework.

This is actually one of the largest instances of savings for the minification of localized strings we have seen. It's common to have comments and whitespace in localization files to be more legible for translators. While useful for translators, there's no reason comments need to be on a user's device. For myChevrolet, the bigger issue is that many of their localization files contain unicode characters.

Screenshot of unicode in chevy localization files

By minifying their localization files with this one Python script, the GM apps could shave off 35+ MB (5% - 8%) of install size 🤯

Screenshot of unicode in chevy localization files

Here are other apps that have high possible minification savings (+ a thread diving into FedEx):

AppMinifying Localization Savings (MB)
FedEx63.2 MB
Night Sky38.0 MB
myChevrolet36.4 MB
myCadillac36.4 MB
myGMC36.3 MB
Garmin Connect25.1 MB
Yahoo Mail23.4 MB
myBuick23.3 MB
trivago18.5 MB
Pages16.5 MB
Webex Meet13.4 MB
Teams13.2 MB
Nike Run Club12.3 MB
Trello11.2 MB
If you're interested in optimizing localization files, here's how Airbnb reduced the size of their localizations by 82%.


The GM apps have many opportunities to reduce their mobile app size. By minifying localized strings, using asset catalogs, removing duplicate files, optimizing images, and removing app-specific images, GM can reduce the size of each app by ~35% (773+ MB total across all their apps). According to Spotify, this reduction in app size translates directly into lower data transfer volumes during app downloads and updates, resulting in measurable reductions in carbon emissions associated with digital data transmission. Because their apps share a lot of code, these low-hanging fruit fixes can help make a big impact.

Analysis Links

Here are the links to all build analysis pages referenced:

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