What is OES™?
How Orbis Measures Real-World Vehicle Efficiency
The VW Tiguan in front of you has a WLTP fuel economy figure of 287.2mpg.
It is actually returning 37.7mpg.
That is not a fault. The vehicle is working exactly as it was designed to work. The gap between those two numbers is not a mechanical problem — it is an information problem. And it is the problem that OES™ was built to solve.
What is OES™?
OES™ — the Orbis Efficiency Score — is a proprietary scoring system that measures how closely a vehicle's actual fuel or energy consumption tracks against its manufacturer specification. It is calculated from real consumption data pulled directly from the vehicle via OEM-native APIs, and expressed as a score from 0 to 100.
OES™ is a trademark of Orbis IO Ltd, currently registered with the UK Intellectual Property Office.
Unlike a trip computer reading or a telematics estimate, OES™ draws from the same data systems that power the vehicle's own onboard computers. There is no dongle. There is no hardware installation. The data is already there — Orbis surfaces it.
How OES™ is Calculated
For ICE and hybrid vehicles, OES™ compares actual MPG derived from real fuel consumption telemetry against the manufacturer's WLTP specification for that specific vehicle variant.
For EVs, it compares actual kWh/100km against the OEM's rated consumption figure, cross-referenced against a database of real-world benchmarks across 130+ EV models.
The resulting score reflects not just the raw efficiency figure, but how far it deviates from what should be achievable given the vehicle type, age, and usage profile.
Score Rating What it means
85–100 ExcellentBeating or matching the OEM real-world benchmark
70–84GoodWithin 10–15% of specification55–69
Average15–25% below specification — investigate40–54
Poor>25% below specification — action required
0–39CriticalSignificant deviation — maintenance or behaviour issue
A Live Example: Tiguan e-Hybrid PHEV
A Volkswagen Tiguan eHybrid PHEV currently operating on a UK fleet monitored by Orbis IO. Here is what 799 telemetry readings — covering 4,090 miles of actual driving between December 2025 and April 2026 — reveal.
Published WLTP combined MPG: 287.2
True combined MPG — 90 days (telemetry-verified): 46.9
OPCI™ Score: 42 — Non-Compliant
Annual fuel waste vs regular charging: £1,176
Battery depleted: 81% of the time
The gap between 287.2mpg and 46.9mpg is not primarily an engine problem. The petrol engine on this vehicle is performing reasonably well — when measured in isolation during depleted-battery segments, it returns 33.2mpg, close to its standalone ICE specification.
The problem is the electric drivetrain. It is contributing almost nothing.
A note on data windows: OES™ measures efficiency over the last 30 days. At the time of this analysis, the Tiguan had been off the road for an extended period awaiting repair. The 30-day OES™ window therefore captures only light use — short journeys to and from the repair centre with a charged battery — which produces a temporarily elevated MPG figure that is not representative of the vehicle's normal operating profile. The 90-day OPCI™ window captures the full picture: the heavy driving period before the repair, the idle period, and the return to service. For a vehicle with an unusual recent history, the longer lookback window is the more reliable representation of real-world efficiency.
Of 799 fuel and battery readings captured over four months, 649 — 81% — show the battery as depleted. Only 48 readings (6%) show the battery above 50%. This vehicle's 74.4-mile electric-only range, which is what produces the 287.2mpg headline figure, is available for roughly one journey in sixteen.
What the Four Operating Modes Show
Orbis's telemetry captures this vehicle in four distinct operating states, each with its own efficiency signature.
Depleted battery (81% of journeys): 33.2 MPG
The battery is flat. The petrol engine carries the full load. 168 separate driving segments, 290.5 litres consumed, 2,124 miles driven. This is how this vehicle operates most of the time.
EV-assist (rare — 6% of journeys): 88.0 MPG
The battery is contributing. 14 segments, 21.5 litres consumed, 416 miles driven. When this vehicle uses its electric drivetrain, it performs close to its design intent. It just rarely does.
Mixed (partial battery, 21% of journeys): 39.9 MPG
The battery has some charge but is depleting. Transitional mode, broadly in line with the depleted figure.
Battery charging from engine: 28.2 MPG
The engine is actively charging the battery. The least efficient mode of operation — consuming more fuel than any other state.
The true combined MPG from real fuel telemetry: 46.9 MPG. Against a published WLTP of 287.2mpg, that is an 84% shortfall — and an annual fuel cost £1,176 higher than if the vehicle were charged regularly.
Why OES™ and OPCI™ Tell Different Stories
OES™ scored this vehicle 76 — Good. That is accurate. The petrol engine is near specification.
OPCI™ — the Orbis Plug-in Compliance Index — scored it 42 — Non-Compliant. That is also accurate. The plug-in system is not being used as the manufacturer intended.
These scores are designed to be read together, not instead of each other.
OES™ answers: is the engine working efficiently?
OPCI™ answers: is the electric drivetrain being used?
A vehicle can score well on OES™ and still represent a significant efficiency and ESG problem — because OES™ is measuring the engine's performance, not whether the PHEV strategy is working. The Tiguan is the proof of that. Petrol engine: near spec. Electric utilisation: 6% of the time.
The published CO₂ figure for this vehicle is 30g/km. When the battery is depleted and the petrol engine is carrying the full load — which is 81% of this vehicle's operating time — actual CO₂ is estimated at 1.5 times the declared figure. If this vehicle appears in an ESG or SECR report at 30g/km, that report is wrong.
The Score the Dashboard Caught
There is a fourth data point on Tiguan that sits outside the efficiency scores entirely.
Current odometer: 27,409 miles. Scheduled service interval: 19,400 miles.
This vehicle is 8,009 miles past its service due date.
Orbis's OPM™ system — Orbis Predictive Maintenance — flagged this automatically. The fleet manager has the information. The question is whether the process exists to act on it.
This is what fleet intelligence is for. Not efficiency percentages that make sustainability reports look better. A service interval that has been exceeded by 8,000 miles on a vehicle that someone is driving today.
What to Check on Your PHEV Fleet
If you run plug-in hybrids and have not looked at actual battery utilisation data, the Tiguan profile is unlikely to be an outlier.
Are your PHEV efficiency figures based on WLTP? If drivers are not consistently charging, your SECR carbon report may be materially understated — not by a small margin, but by a factor of up to 1.5 times the declared figure.
Do you know how often your PHEV batteries are depleted? An OES™ score of 70+ on a PHEV tells you the engine is working. It does not tell you the PHEV strategy is working. That requires OPCI™.
Do you know your vehicles' actual service status? OPM™ tracks service intervals against real odometer data pulled from the vehicle. Not from the service history file. From the vehicle itself.
Are any vehicles past their service interval right now? On a fleet of any size, the probability is high. The question is whether you have the data to know which ones.
The Four Orbis Scores
OES™ is one of four proprietary scores Orbis IO applies to every connected vehicle.
OES™ — Orbis Efficiency Score
Actual fuel or energy consumption vs OEM specification. 0–100.
ORS™ — Orbis Risk Score
Driver behaviour: braking, acceleration, cornering, speed. Insurance-relevant. 0–100.
OPCI™ — Orbis Plug-in Compliance Index
Charging frequency and battery utilisation for PHEV and EV vehicles. 0–100.
OBI™ — Orbis Battery Index
Battery health, degradation trajectory and range retention for EV fleets.
Together they give a fleet manager a complete picture of what is actually happening across their vehicles — drawn from data the vehicles are already generating.
Not estimates. Not averages. Not what the manufacturer claims under test conditions.
What the vehicle actually knows.
A Note on Data Windows and Score Confidence
The OES™ 30-day score for our Tiguan currently shows 68.8 MPG — higher than the 46.9 MPG figure used in this article. That is not a contradiction. It reflects a period where the vehicle had minimal activity during a service stay and made shorter journeys with proportionally more electric assist than during normal operation.
Orbis surfaces both figures because context matters. The efficiency trend — built from historical data across normal operation — shows 41 MPG, consistent with the OPCI 90-day figure. When the 30-day window diverges significantly from the historical trend, Orbis now flags the anomaly automatically:
"Current 30-day MPG (69) differs significantly from historical trend (38 MPG). This may reflect a low-activity or atypical period."
When fewer fuel measurement exist in the window, Orbis flags low data confidence and notes how many segments the score is based on. A score without confidence weighting is just a number.
This matters for fleet reporting. A vehicle returning from a service centre will briefly show an inflated efficiency score. A vehicle handed to a new driver will show a score influenced by the previous driver's behaviour. Orbis distinguishes between the score and the confidence in that score — and surfaces both to the fleet manager.
Orbis IO connects directly to your vehicles via OEM-native APIs — no hardware, no installation.
We'll show you what OES™, OPCI™, ORS™ and OBI™ surface from your vehicles on day one.
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