LEGO 42109 App-Controlled Top Gear Rally Car Review
- Published
- March 22, 2026
- Pieces
- 463
- MSRP / street
- $129 USD
BrickScore breakdown
- Build quality8.5/10
- Value6.8/10
- Instructions9/10
- Design7.8/10
The LEGO Technic 42109 App-Controlled Top Gear Rally Car is a playful entry point into app-controlled Technic: a short chassis, quick build, and immediate payoff the moment you pair it with the Control+ hub and motors. It's LEGO's one and only Top Gear tie-in, complete with Stig branding, and it remains one of the smallest remote-controlled cars LEGO has ever made.
What you get in the box
The real reason this set costs $129 isn't the brick count — it's the electronics. Inside you get a Control+ Smart Hub, one XL motor for drive and one L motor for steering. Building can start without batteries, but to actually drive it you'll need six AA batteries (not included) and the free LEGO Technic CONTROL+ app on a compatible phone or tablet.
- Set number: 42109
- Theme: Technic (Control+)
- Pieces: 463
- Price: $129.99 at release
- Age: 9+
- Electronics: 1 Smart Hub, 1 XL motor, 1 L motor
- Power: 6 x AA batteries (not included)
- Finished size: ~10 in. (26 cm) long, 5 in. (14 cm) wide
- Build time: ~3 hours
What works
LEGO's digital instructions remain the gold standard here — clear angles, smooth rotation, and smart callouts for orientation-sensitive steps. The model is sturdy enough for indoor runs on smooth floors, and the drivetrain is approachable if you're new to geared layouts. Once you're paired, the app gives you two steering modes: standard twin-thumb controls, or a gyro mode where you tilt the phone to steer. The gyro mode is the more fun of the two, and there's a surprising amount of extra content baked in — a speed-and-tilt telemetry log and a racing-challenges section.
Pros
- Excellent instructions and beginner-friendly Technic pacing
- Control+ integration feels polished and responsive
- Gyro steering mode is genuinely fun
- Compact footprint - easy to store when play wraps up
Cons
- Price-per-piece is steep once you factor in the electronics
- Top speed is underwhelming for a rally car
- Low ground clearance means smooth indoor floors only
- Display presence is modest compared to larger Technic cars
Who it's for
If you're buying primarily for play, this is an easy recommend — and the cheapest way into LEGO's Control+ ecosystem, since the motors and hub alone are worth most of the asking price. If you're optimizing for static display value or long build hours per dollar, larger non-powered Technic sets win — but they won't replicate the same RC grin. For more on the value-vs-play trade-off, see our take on the LEGO 60447 Off-Road Mountain Truck and the CADA C4 Supercar.
Is the LEGO 42109 Rally Car worth it?
A confident 7.8: premium LEGO execution with a value story that only fully lands if you'll actually drive it. Buy it for the motorized play and the Control+ intro, not for the parts count — and if you can catch it on sale, it gets a lot easier to recommend.