Completing a lap around the test track in LEGO Technic 42109 App-Controlled Top Gear Rally Car [Review]

Some say that LEGO is only meant for kids and season 3 of Top Gear was the best one. All we know is LEGO and the BBC are bringing a very special LEGO Technic set, 42109 App-Controlled Top Gear Rally Car, and it is powered by a couple of new Powered Up motors. Thanks to Bluetooth connectivity, the car can be controlled via an app installed on a smartphone or a tablet. Despite the smart elements under the bonnet, the model consists of just 463 pieces, which makes it one of the smallest LEGO remote-controlled cars ever released. The set comes with a price tag of US $129.99 | CAN $179.99UK £124.99 and is already available in stores.

The box and the packaging

A medium-sized box doesn’t feel like one containing a toy worth 120 bucks. Inside are just 5 bags, the building guide, and a black box with electrical elements, that are accountable for the major part of the set’s price.

Fun fact: while the new box of motors carries number 6301301, a similar box with identical contents from LEGO Technic 4×4 X-treme Off-Roader (42099) set was labeled 6280535. Now, you can easily tell which set the box comes from.

No doubt, this small black box is the sole reason to purchase the set. We’ve been waiting for a smaller set with the new electric elements since August, and we are finally getting one. If you are looking forward to building your own models with the new motors, you don’t have to read till the conclusion of this review; the set is the best chance to try out the new motorization possibilities.

Like many other modern LEGO Technic models, the design of this car is mostly created by a couple of dozens of stickers.

New and interesting pieces

A 460-piece set can hardly introduce a lot of new pieces. However, there are a couple of elements designed for this rally car. As we have learned while building 42100 Liebherr R 9800 Excavator set, the new Powered Up motors are among the most powerful LEGO motors to date, producing a ton of torque. The more powerful motors require stronger transmissions, and in the case of the rally car — a stronger differential. LEGO Technic builders will know that the regular differential is not the most reliable solution especially when exposed to the extreme pressure inside custom off-road trucks. To make the toy as rugged as possible, here comes a new type of differential casing.


Instead of just three thin gears, the casing houses 5 gears, 3 of which are set at an angle of 60 degrees relative to each other. I find it fascinating that the small tan gears inside the differential were first introduced in 1993, while the new casing is being released more than 25 years later. The design of the gear is so simple and universal, that it didn’t require any updates to fit into the new mechanism.

It would take a couple of paragraphs to describe the way the differential is assembled, but a picture from the building guide is worth a hundred words:

With the new casing comes yet another specific gear — a red angled gear with 28 teeth. Earlier this year another 28-tooth gear was introduced, which was hailed enthusiastically by Technic fans. Unlike that grey gear, this new red one looks a lot less promising. Because of the clearance hole, the gear can’t be used with cross axles to transfer rotation. This is highly specific gear to be used with the new casing, hence the rectangular openings in the middle part of the gear.


The gear clicks softly over the casing and serves as a “lid” concealing the gears inside. This part can be easily disassembled when needed.


Kids anticipating the impending rally race around the house will be even happier to learn that thanks to the set’s small size, even an inexperienced builder can finish the model in one evening long building session. No part of the car is too complicated to build and test, but the set quite nicely demonstrates the best use of the recently introduced elements, like the large Technic frame.

There will be a handful of things to criticize the set for, but I must admit that the chassis is a very solid build. It is very robust and compact, which makes it a perfect platform for custom remote-controlled cars.

With the rest of the pieces, the car’s body is assembled. Smaller mudguards work perfectly for a model of this scale.

Finished model

Before heading out to the test track, we are taking a closer look at the car’s design. Since the moment the first official product pictures were published online, a lot of LEGO Technic fans called the car’s look very questionable. The reason for the controversy is the combination of panels and arches of several colors, which make it look like a patchwork. Unfortunately, the stickers make things even worse; red on white, white on blue, black on white — it’s almost impossible to tell which spots create color accents.

Even without the stickers, it’s hard to praise the shape of the car’s body. Usually, it’s very easy to create seamless shapes when building with LEGO Technic panels, but the design of this model breaks way too many rules. Take a closer look at the rear end of the car: there is no harmony among the panels with every single one facing a different direction sticking out from the middle of the structure. The black panel with a dark blue gradient sticker is surrounded by pieces in red and black, while a couple of weird-looking vertical panels in dark blue border on panels in white. What a crazy quilt..!

The front of the car doesn’t look much better, but at least the shape and the lines look nicer. One defense for the looks might be to say that the car was designed for rough play, but this is very questionable, too. For instance, the headlights are sitting on just a couple of studs each, which is never a secure way to attach pieces.

The longer you examine the car, the more questionable its durability and fitness for remote racing seem to be. Obviously, the car was designed for indoor play only. But since the road clearance is so small, I fear that with the new red gear sitting as close to the ground as possible, it will quickly accumulate all the dust and pet hairs around your house. It will take more tests to find out if the toy’s performance will drop over time.

The toy’s branding

We love when LEGO collaborates with automakers and releases branded models based on existing vehicles (like the recent 42110 Land Rover Defender set). What we do not expect from LEGO is a collaboration with a TV show. I mean, a lovely 21319 Friends Central Perk set was the nicest surprise. But when we speak about LEGO Technic cars, BBC’s Top Gear licensed set isn’t something obvious. BBC does not produce cars, and the essence of the Top Gear TV show is the trio of hosts (whether old or new). LEGO building toys with Bluetooth connectivity and a TV show full of witty dialogs about cars and spectacular crashes feel like a couple of quite different things. However, they managed to find the only thing that connects the two worlds, and its name is The Stig.

And so we arrive at a no-name rally car that is allegedly driven by Stig. I remember watching Top Gear 8 or 10 years ago when everyone was talking about it as one of the best TV shows of the time. That was the time when the character of Stig became truly iconic; a mysterious driver in a white racing suit. My friends and I even built minifigures of Stig using white torsos and helmets with black visors. But that was many years ago. I must admit I haven’t seen the most recent episodes of the show, but I haven’t heard about Stig in media or on the Internet since then. I wonder if the character is popular among modern kids and teenagers, but I doubt it can be a strong selling point for the set.

The smart app and playability

Finally, it’s time to start the engine — or, in this case, a smart hub. With the release of the set, the Control+ mobile application got an update, too. You can download it right now (Android, iOS), and in case you’ve already got a set of the new Powered Up elements, you can plug the motors into the hub and try out the interface without purchasing the new rally car. Obviously, the car can only go forward and backward, turn left and right. The description of the functions takes just one page at the end of the building guide.

When building the set and preparing the review, I was expecting that the description of the app and play experience will take a considerable part of the review. This is because both of the earlier Control+ sets, 42099 4×4 X-treme Off-Roader and 42100 Liebherr R 9800 Excavator, introduced brand new ways of play into the LEGO Technic universe. Honestly, I was expecting the new rally car with a smart hub to be something more than just a regular remote-controlled toy, but, unfortunately, it is just a remote control toy. A picture from the App Store perfectly summarises the features of the app: you can drive the car in 2 modes (by tapping the screen, or by tilting your smart device to steer), as well as complete a number of challenges.

Smart App

One of my favorite things about the 42099 Off-roader set was the “magical” one-touch control. Honestly, I was absolutely sure this play mode would be borrowed for the rally car, but it turns out it wasn’t.

The other thing that definitely doesn’t give the model any bonus points is the programmed limitation of the driving motor’s speed. The app can simulate both types of transmission so that the car accelerates or slows down depending on the gear activated in the app. This software feature works nice, but it limits the possibilities of the new motors dramatically. Even in the highest gear, the car goes slower than a pull-back LEGO Technic set. Fortunately, there are already a number of fan-designed third-party applications that can let you connect and control the new Powered Up motors. Using one of those apps, you can make the motors run at their highest speeds. Immediately, controlling the car becomes ten times more interesting and exciting. Obviously, using third-party apps does not guarantee that the hardware functions as intended by LEGO, so install, connect and play at your own risk.

Final thoughts and conclusion

The new Powered Up platform is still being developed by LEGO. Although 3 sets containing the new motors have been released within the Technic lineup already, the full potential of the new system is yet to be discovered by either the developers or the fans. No doubt, the new LEGO Technic 42109 App-Controlled Top Gear Rally Car set served a single purpose — to give the customers the cheapest functional model possible containing the full set of new electric elements. And the set does this job perfectly; you get the motors and a simple model to try out the new pieces.

However, this set feels very, very underwhelming after a couple of fantastic models released back in August (42099 4×4 X-treme Off-Roader) and October (42100 Liebherr R 9800 Excavator). Neither the actual mechanisms nor the software reveals half of the platform’s potential. In fact, it’s a very expensive toy that carries a bunch of sensors and a couple of well-engineered motors, but it is not capable of any truly special tricks. Considering the price of the set, it would make much more sense to save up a little more and get an impressive 42099 4×4 X-treme Off-Roader, or even Liebherr R 9800 Excavator; both have a lot more value for the money. Some say that any LEGO set is better than no LEGO at all. All we know is not all LEGO Technic sets are equally cool and worth a purchase.

LEGO Technic 42109 App-Controlled Top Gear Rally Car comes with 463 pieces and is available starting today, December 26th for US $129.99 | CAN $179.99UK £124.99, as well as some third parties on Amazon, Bricklink and eBay.

The LEGO Group sent The Brothers Brick an early copy of this set for review. Providing TBB with products for review guarantees neither coverage nor positive reviews.

6 comments on “Completing a lap around the test track in LEGO Technic 42109 App-Controlled Top Gear Rally Car [Review]

  1. HellxKnight

    In your paragraph about the differential you wrote 60 degrees relative to each other. You meant 120.

  2. Felicia Barker

    ‘to give the customers the cheapest functional model possible containing the full set of new electric elements.’

    And yet they made it a licensed product (and a bizarre license at that), which would seem at odds with that goal.

  3. winston

    i won’t pretend to know how licensing deals work, but i wonder if the rumored Top Gear set that was in the works a few years back before the original cast moved to amazon has to do with this. maybe the license was set to expire and they wanted to put something out beforehand?

  4. Alex

    No, it is 60 degrees since they form an equilateral triangle, not a hexagon. It would require 6 gears at an angle of 120 degrees to form that hexagon.

  5. Jimmy

    I don’t mind the wild styling, WRC cars seem to have all sorts of fins and strakes and flares and such. What bugs me the most is the stupid tire sizes, all four should match.

    P.S. I’m with HellxKnight, bevel gear geometry is described using the rotation axis of the gears (i.e. the shaft the gear would rotate on, if there was one). The axes of those gears is 120° apart. (though we all get what you mean).

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