Recommended: Yes.
For a foundational start - It's a great start.
The physics-based gameplay is simple, fun and has a nice variety of vehicles.
It's definitely the type of Indie Game you'd likely see on Steam Next Fest or other indie fests. Can also see the project being enjoyable on both PC and Mobile. The optimisation is great.
Feedback:
1) Post-Match. Let players vote on which Map they want to do next.
2) Add AI Vehicles. This is because S&Box has a small community. And players are unlikely to stick around(unfortunately). AI Vehicles would enhance the experience. As soon as a Player enters, the AI Vehicle is replaced with that Human Player.
3) I would decrease the Match Time by 50%. Again due to the small S&Box playerbase, as well as Player Concentration Levels within the Gmod community. Players tend to jump around alot. They very rarely stick around for long periods. If you decrease the Match time, you'd have to decrease the car timer to match.
In terms of timing/gamemode. In the future you could have a Blitz mode, which is alot quicker and more focussed on plenty of carnage. Rather than Survival Gameplay.
4) Art style/physics/sounds are all great. I'm sure you'll look at implementing weather and maybe other complex systems in the future. For now? It's a great start.
5) If you don't find much success on S&Box, I wish you well in the future.