Because you've got it set to Summer. Change the style to Winter.
Looks like HLMV doesn't allow for style changes
What's this "TFMV"?
Team Fortress Model Viewer, it's a GUI that allows you to quickly add items to the player model and look at it in Half-Life Model Viewer, it was initially for modders so they could easily see what their models would look like when in use but the general public started using it as a way to preview loadouts since itemtest is such a pile of stuff
Facepunch appears to be down so here's the gamebanana page if you're interested
This sentry spot on upward + wrangler + pub server = hilarity
The cart was rolling almost non-stop until it hit this point and didn't get any further the entire game, they probably would've gotten passed if someone had gone Spy earlier than the last 15 seconds