A newer engine hiding behind a familiar badge. Exactly which models got the AJ20D6, which got the outgoing 306DT V6 under the same D300 name, why JLR does this, and how to tell them apart.
If your Land Rover is badged D300 or D350, it could be either the 306DT V6 or the newer AJ20D6 straight-six - the badge alone doesn't tell you, and the two are completely different engines under the skin.
Full model-by-model fitment table below, plus how to confirm which engine your specific vehicle has.
Every model and badge where the AJ20D6 replaced the 306DT, and the point at which the switch happened.
| Model | Badge | 306DT Years | AJ20D6 Years | Notes |
|---|---|---|---|---|
| Range Rover L405 | D300 / D350 | 2018–2020 | 2020–2021 | Overlapping changeover window [VERIFY] |
| Range Rover L460 | D300 / D350 | - | 2022–present | AJ20D6 from launch, no 306DT fitment |
| Range Rover Sport L494 | D300 | 2018–2020 | 2020–2022 | Late L494 only |
| Range Rover Sport L461 | D300 / D350 | - | 2022–present | AJ20D6 from launch |
| Velar L560 | D300 | 2017–2020 | 2021–present | The flagship badge-ambiguity case - see Velar D300 Variant Page |
| Discovery 5 L462 | D300 | 2017–2020 | 2021–present | Follows the same pattern as Velar |
Model years marked [VERIFY] should be confirmed against a specific VIN before publishing an exact cutoff to a customer - changeover points frequently span a model year rather than falling on a single date.
JLR names badges after power output, not engine architecture - which is exactly why this confusion exists.
"D300" describes a diesel producing roughly 300PS. When the outgoing 306DT V6 was replaced by the newer AJ20D6 straight-six, both engines were tuned to produce approximately the same power figure, so both qualified for the same badge. From a marketing standpoint this makes sense - the badge tells a buyer what the car will feel like to drive. From an engine-identification standpoint, it means the badge alone is genuinely useless for working out which physical engine you have [PATTERN DATA]. This is not unique to the D300 badge - the same pattern occurs on the petrol side with P400, and JLR has used this naming convention consistently across the range for over a decade, which is worth knowing if you're researching a different badge and assuming the number tells you the engine family.
Located on the block, typically visible from above without removing panels. The prefix identifies the family - full location diagram on our Engine Number Location guide.
The fastest method. Our Registration Lookup tool cross-references your plate against build data instantly.
The AJ20D6 has a noticeably different rocker cover shape and a single, larger turbocharger housing compared to the 306DT's twin-turbo layout.
The two engines are not interchangeable in any sense that matters to a buyer. Mounting points, ECU calibration, ancillary compatibility and even the physical dimensions of the block differ enough that a supplier quoting for "a D300 engine" without confirming which architecture you actually have is quoting blind. Ordering the wrong one means a return, a delivery delay, and in most cases a second shipping cost on top of the original - entirely avoidable by confirming the exact engine code before requesting a quote, not after.
The specific wrong answers people arrive at, and why.
No. They are two genuinely different engine families that happen to share some badge names. The 306DT is a 3.0 V6 diesel used from roughly 2010-2021. The AJ20D6 is a newer 3.0 straight-six diesel that began replacing it from around 2020-2021, badged D300/D350 in some models.
Check your build date. Most D300-badged models switched to the AJ20D6 from the 2021 model year onward, though the exact changeover point varies by model. The most reliable method is checking the engine number stamped on the block, or using our VIN decoder tool.
It is a newer engine, so our enquiry dataset is still building. Early indications from our 2025 data are positive, with no catastrophic failure pattern yet comparable to the 306DT's crankshaft bearing issue. We will update this page as more real-world mileage accumulates.
JLR badges describe approximate power output rather than engine architecture. Both the outgoing 306DT and the newer AJ20D6 were tuned to produce roughly 300PS, so both qualified for the D300 name even though they are mechanically unrelated.
No SpeculationWhere a fitment year isn't confirmed, we say so - never a confident guess.
Cross-ReferencedFitment data checked against multiple independent parts and specialist sources.
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