Introduction | The Limits of Gear Selection in the GR-DAT
I own two Toyota GR Yaris RZ High Performance models: a 2020 car with a six-speed manual transmission (6MT) and a 2024 model with the eight-speed GR Direct Automatic Transmission (GR-DAT).
I regularly drive both cars on track.
The GR-DAT is an exceptionally capable transmission.
Its shifts are quick, and its eight ratios allow it to make effective use of the engine’s power delivery. In D mode, the transmission also takes care of gear selection, leaving the driver free to concentrate on braking, throttle control, and steering.
I have been particularly impressed by how well the GR-DAT performs under acceleration.
However, the more time I spend driving it on track, the more I notice a particular limitation.
The gear selected by the GR-DAT is sometimes different from the one I want to use.
Even when I try to correct its choice using the paddle shifters in D mode, the electronic control system may prevent the requested shift. Electronic intervention also occurs in M mode.
In my experience, these limitations are more noticeable under braking than under acceleration, especially on circuits with successive slow corners and frequent elevation changes.
This raises an interesting question.
Despite the GR-DAT’s advantages in shift speed and number of ratios, could a skilled driver who knows a circuit thoroughly still achieve a faster lap in a six-speed manual?
And what capabilities would an automatic transmission need to consistently outperform such a driver?
1. The Right Gear Depends on What Comes Next
Setting a fast lap requires high speeds on the straights, but it also demands efficient transitions through braking, cornering, and acceleration.
At the end of a straight, the driver brakes hard to reduce speed. As the car approaches turn-in, brake pressure is gradually released while steering angle increases. This is known as trail braking.
Around the apex, the driver begins to feed in throttle while progressively unwinding the steering wheel, transferring the tires’ available grip from cornering to acceleration.
A skilled driver manages these transitions continuously, making the most of the limited grip available from the tires.
Gear selection is an important part of that process.
Consider two situations in which the car has exactly the same speed, deceleration G, and brake input.
In one, a tight hairpin lies ahead. In the other, the next corner is a fast sweeper.
The most appropriate gear may be different, even though the car’s current operating conditions are identical.
Similarly, when several corners follow one another, holding a particular gear through the entire sequence may be preferable to shifting between them.
The right gear depends on both the car’s current state and what the driver intends to do next.
From this perspective, effective gear selection requires three capabilities:
- Information gathering: Understanding the car’s current state and the road or circuit conditions ahead.
- Decision-making: Determining the appropriate gear and shift timing from that information.
- Execution and gear holding: Completing the shift when required and maintaining the selected gear for as long as necessary.
These three capabilities determine how effectively a transmission can exploit its mechanical performance.
2. The GR-DAT and a Skilled Driver Have Access to Different Information
The GR-DAT uses vehicle data and driver inputs to determine which gear to select.
According to Toyota’s official announcement of January 12, 2024, the transmission considers vehicle speed and deceleration G, as well as how the driver applies and releases the brake pedal and operates the accelerator.
By interpreting these inputs, the GR-DAT attempts to anticipate the driver’s intentions and initiate shifts before the resulting vehicle behavior becomes apparent.
In practice, its gear choices in D mode are appropriate in many situations.
A skilled driver, however, makes decisions using additional information about the circuit ahead.
Suppose a right-hand corner is immediately followed by a left-hander.
Before entering the first corner, an experienced driver is already considering how to position the car for the second corner and how to accelerate out of it.
The driver also considers upcoming gradients, banking, the intended racing line, and the amount of drive needed on corner exit.
On a familiar circuit, an experienced driver has learned far more than what is currently visible through the windshield.
Braking points, corner speeds, gear choices, and even sections of track beyond the driver’s immediate field of vision are already known.
The 2024 GR-DAT primarily predicts the appropriate gear from the car’s current state and the driver’s inputs. A skilled driver who has mastered the circuit chooses a gear with knowledge of what lies ahead.
That difference in available information matters.
The 2024 GR-DAT does not use a forward-facing camera to recognize the road geometry ahead and incorporate that information into its shift decisions.
Consequently, improving the way it interprets vehicle data and driver inputs can only go so far.
A driver who knows the circuit has information that the transmission does not.
I believe this is one of the fundamental limitations of the current approach to automatic gear selection.
3. Both D Mode and M Mode Impose Limits on Gear Selection
Beyond the information available to the transmission, the GR-DAT also imposes restrictions on executing shifts.
D Mode: The Paddles Set an Upper Gear Limit
In the 2024 GR-DAT, the paddle shifters allow the driver to intervene while remaining in D mode.
However, this intervention primarily selects a shift range by specifying the highest gear the transmission may use.
For example, selecting D3 allows the transmission to shift automatically within a range that goes up to third gear.
The selected range may also be cancelled automatically under certain conditions, including sustained accelerator input.
Furthermore, the official 2024 GR Yaris owner’s manual explains that downshift requests may be restricted to protect the vehicle and maintain appropriate driving performance.
Under certain conditions, a requested downshift will be rejected and a warning buzzer will sound.
M Mode: Electronic Controls Still Have the Final Say
In M mode, the driver can request a specific gear using either the paddles or the shift lever.
Even here, the transmission retains authority over certain decisions.
According to the owner’s manual, the GR-DAT may shift automatically when engine speed is approaching an excessively high or low level.
A requested downshift may also be refused, in which case the transmission alerts the driver with a buzzer and a flashing gear indicator.
Thus, even in M mode, electronic controls determine whether a requested shift can be executed and whether the selected gear can be maintained.
A driver may correctly identify the desired gear yet still be prevented from using it by the transmission’s control system.
4. Is the GR-DAT Using a Generous Safety Margin for Downshifts?
In my 2024 GR-DAT, electronic intervention is particularly noticeable during downshifts under braking.
One important factor is the engine speed that would result from a requested shift.
During a normal upshift under acceleration, engine rpm falls.
During a downshift, engine rpm rises according to the lower gear’s ratio. At sufficiently high vehicle speeds, the resulting rpm could exceed the engine’s permissible operating range.
It therefore makes sense for the transmission to restrict downshifts based on predicted engine rpm.
Here is my hypothesis.
I suspect that the 2024 GR-DAT may set its downshift-permission threshold substantially below the engine’s actual mechanical tolerance, leaving a generous safety margin.
If so, that margin would narrow the range of vehicle speeds at which a downshift is permitted.
There may be situations in which the engine could safely tolerate the rpm resulting from a lower gear, yet the transmission refuses the shift because its programmed threshold has been reached.
If the GR-DAT rejects downshifts within an engine-speed range that can safely be used, that creates a difference in gear-selection freedom between the automatic and a manual transmission.
I do not know the GR-DAT’s precise downshift-permission thresholds or the size of its safety margins.
Transmission protection and vehicle stability may also influence these restrictions.
Nevertheless, I suspect that the calibration of these protective controls contributes to the downshift limitations I encounter on track.
5. How Shift Restrictions Can Affect Lap Times During Braking and Turn-In
Imagine approaching a corner at high speed and planning to take it in third gear.
The driver brakes hard, intending to complete the downshifts before turn-in.
However, the GR-DAT may initially reject the shift into third because vehicle speed is still too high.
The driver must either wait until speed has fallen sufficiently or enter the corner in the current gear.
The important issue is shift timing and its effect on the car’s balance.
During initial braking, much of the tires’ available grip is being used to slow the car.
As the driver releases brake pressure and adds steering angle, progressively more grip is needed for cornering.
A shift at that point can change the torque at the wheels and unsettle the car.
Ideally, the required gear is already engaged before the transition into the corner. The driver can then concentrate on coordinating brake release and steering input.
This becomes especially important on technical circuits with successive slow corners and frequent elevation changes.
Consider a downhill braking zone leading into a right-hander, followed immediately by a left-hander and an uphill acceleration zone.
In such a section, choosing a gear for the entire sequence and holding it may help keep the car settled by avoiding unnecessary changes in drive torque.
If the GR-DAT selects a different gear in D mode or refuses a downshift in M mode, the driver must adapt to the gear actually available.
I previously discussed how the GR-DAT frees up mental capacity for observing the road and controlling the car in What I Learned from Driving Both the Six-Speed Manual and Eight-Speed GR-DAT GR Yaris on Track.
However, monitoring and correcting the transmission’s gear choices also demands attention.
The timing of engine braking is another factor affecting vehicle balance. I explored that subject in GR Yaris 6MT vs GR-DAT Brake Wear: Braking Energy and a Hypothesis About Lock-Up Control.
During the transition from braking to cornering, having the right gear engaged at the right moment allows the driver to manage the car’s behavior as intended.
6. Three Conditions Under Which a Six-Speed Manual Can Beat the GR-DAT
For a six-speed manual to produce a faster lap than the 2024 GR-DAT, I believe three conditions on the driver’s side are particularly important.
1. Advanced Performance-Driving Skills
The driver must be able to manage the car close to the limits of tire grip, transitioning smoothly from hard braking to trail braking and balancing steering angle with throttle input through corner exit.
In a manual car, the driver must also execute clutch operation and rev-matched downshifts, including heel-and-toe, accurately while performing these tasks.
2. Thorough Knowledge of the Circuit
The driver must have a well-established plan for the entire lap, including braking points, corner-entry speeds, racing lines, gear choices, and corner-exit strategies.
That knowledge makes it possible to select gears based on the upcoming sequence of corners rather than reacting only to the car’s current state.
3. The Ability to Complete a Mistake-Free Lap
To translate driving skill and circuit knowledge into a fast lap time, the driver must execute the planned inputs accurately.
Even small mistakes in braking points, speed reduction, gear changes, steering, or throttle application can cost time.
This third condition highlights an important difference between human drivers and machines.
An automatic transmission can execute gear selection and shifts with high repeatability. A human driver introduces some variation in both shift decisions and their execution from lap to lap.
A skilled driver may record a faster lap in a manual than in the 2024 GR-DAT, yet find it difficult to reproduce that lap consistently.
This gives us two distinct measures of performance: the ability to produce a single fastest lap and the ability to repeat performance close to that level.
To make the most of a manual transmission’s advantages, the driver needs advanced driving skills, a thoroughly mastered circuit, and a mistake-free lap.
In fact, even at my own level, I occasionally record laps a few tenths of a second faster in my six-speed manual than in my GR-DAT on a circuit I know well.
Of course, my two cars differ in ways beyond their transmissions.
| Specification | My 2020 6MT | My 2024 GR-DAT |
|---|---|---|
| Maximum power | 272 PS | 304 PS |
| Maximum torque | 370 Nm | 400 Nm |
| Manufacturer’s stated vehicle weight | 1,280 kg | 1,300 kg |
| Number of gears | 6 | 8 |
My manual car also has modifications to its suspension and controls. Track conditions and weather vary between driving sessions as well.
These differences affect lap times.
Toyota has also stated in its official UK announcement that the GR-DAT achieved faster lap times than the manual during development testing.
My interest here is in the conditions under which the 2024 GR-DAT’s gear-selection logic and shift restrictions may become obstacles to further lap-time improvement, particularly when compared with a skilled driver on a thoroughly familiar circuit.
7. Toyota Has Already Improved the GR-DAT for Later Model Years
Toyota has continued refining the GR-DAT’s shift-control software.
In its April 11, 2025 announcement, Toyota described several improvements, including a wider vehicle-speed range in which drivers can request a second-to-first downshift using the paddles in D mode.
It also shortened the delay between paddle input and the start of a shift, while improving the directness of M-mode operation near the redline when SPORT mode is selected.
Under full-throttle acceleration uphill, the shift-up timing was also revised to maintain stronger power delivery after the shift.
The expansion of the permitted downshift speed range is particularly interesting.
It means that some downshifts previously restricted by the 2024 calibration became available in the 2025 version.
This demonstrates that the transmission’s shift-permission limits can be revised.
The driving impressions discussed in this article come from my 2024 GR-DAT. Later model years have received changes to these control characteristics and should be evaluated separately.
8. What If the GR-DAT Could See the Road Ahead and Learn from Experience?
The development I would most like to see in future automatic transmissions is the combination of forward-looking camera recognition and the ability to learn from driving experience.
A human driver looks at the road ahead, anticipates the braking and acceleration that will be required, and selects a gear accordingly.
A car could do something similar.
A forward-facing camera could identify upcoming corners, changes in gradient, and sequences of bends, then feed that information into the transmission’s shift-control system.
For example, even if vehicle speed, G forces, and pedal inputs were identical, recognizing a tight hairpin ahead would allow the transmission to plan the appropriate downshift and its timing.
On a series of gentle bends, it might instead determine that holding the current gear would be preferable.
Such a system could use the road geometry visible to its cameras even on roads for which no map data had been loaded.
But what if it could also learn from previous laps?
The system could associate visually recognized circuit features and locations with the shifts made there, vehicle speed, G forces, and the resulting acceleration or deceleration.
Over successive laps, it could learn which gears and shift timings work best at different points on the circuit.
On an unfamiliar circuit, it would make decisions using what its cameras can see.
On a familiar circuit, it could also draw on the experience accumulated during previous laps.
This would resemble the way an experienced human driver gradually learns and masters a circuit.
If the system could also evaluate the driver’s racing line, braking points, and available grip alongside the resulting vehicle behavior, its gear-selection decisions could become more accurate still.
Forward-facing camera systems are already widely used in driver-assistance technology to recognize the road environment.
Connecting that recognition capability to transmission control, and adding the ability to learn from driving experience, seems a logical direction for future automatic transmissions.
Today’s GR-DAT selects gears using vehicle data, including G forces, and driver inputs. Adding the ability to see the road ahead and learn from previous driving experience would take automatic gear selection to another level.
9. What Would It Take for an Automatic to Consistently Beat a Skilled Manual Driver?
My ideal automatic transmission would make better gear-selection decisions than a skilled driver at their best, then reproduce that performance consistently from lap to lap.
To achieve this, it would need to recognize the road ahead, learn from previous driving experience, identify the appropriate gear, and execute or hold that gear at the right moment.
Its shift-permission limits would also need to be calibrated to make effective use of the engine’s performance while protecting the engine and transmission.
With those capabilities in place, an automatic could make better use of its inherently quick shifts and closely spaced gear ratios.
The benchmark would be a driver with advanced skills, thorough knowledge of the circuit, and the ability to complete a mistake-free lap.
The automatic would seek to outperform that driver’s gear selection through superior decision-making, shift speed, multiple ratios, and repeatability.
Evaluating such performance would require comparable vehicle specifications and driving conditions, with attention to both the contribution to the fastest lap and the consistency of shift performance over successive laps.
As automatic transmission control improves, we may eventually reach a point where even the best drivers can record faster laps by leaving gear selection entirely to D mode.
Taking the idea further, a fully autonomous vehicle would also decide braking points, racing lines, steering inputs, and throttle application.
At that stage, the challenge would extend beyond the transmission to optimizing the entire lap.
Can a machine consistently beat the fastest lap of a skilled driver who knows the circuit inside out and executes every input without error?
I see that as an ultimate technological objective linking advanced automatic transmissions with autonomous driving.
And even if machines achieve that goal, I believe the value of competition between human drivers will remain.
Computers have already surpassed the strongest human players in chess and shogi, yet professional players continue to compete.
Watching people test their skills against one another has a value of its own.
The same should hold true in motorsport. As machines become more capable, the driver’s role may evolve, but competition between human drivers will continue.
Conclusion | From Fast Shifts to Seeing Ahead and Learning from Experience
My experience with the 2024 GR-DAT points to two limitations in its gear-selection capabilities.
First, its decisions rely primarily on vehicle data, such as G forces, and driver inputs. This limits its ability to account for the road or circuit layout ahead.
Second, even when the driver knows which gear is appropriate, the transmission’s electronic controls may restrict the requested shift.
These limitations may leave an advantage for a skilled manual driver who has thoroughly mastered the circuit and can complete a mistake-free lap.
Meanwhile, Toyota has already begun improving the GR-DAT’s shift-control system.
If future automatic transmissions can recognize the road ahead, learn from driving experience, and optimize the execution of shifts, they will be able to take fuller advantage of their shift speed, multiple ratios, and repeatability.
The evolution of automatic transmissions is moving beyond the question of how quickly a gear can be changed. The greater challenge is understanding what lies ahead, learning from experience, deciding which gear to use and when, and knowing how long to hold it.
The ability to make those decisions accurately and execute them consistently may ultimately allow an automatic transmission to outperform even the most skilled manual drivers.
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