Two names for Land Rover's 3.0 V6 diesel — but they're not the same engine. One is the entry-level workhorse, the other is a higher-output evolution with a different character and different costs. Here's the honest verdict on which one suits you.
The SDV6 is the better engine for most buyers — it produces more power and torque, feels more refined, and is fitted to later, higher-value vehicles where the replacement cost is a smaller percentage of the vehicle's value. The TDV6 is still a capable, proven engine, but it's the older, lower-output variant, and the price difference at replacement time is smaller than you might expect.
Full comparison, running cost breakdown, and which to choose for your specific situation below.
| TDV6 (306DT low-output) | SDV6 (306DT high-output) | |
|---|---|---|
| Engine Code | 306DT | 306DT / 508PS |
| Power Output | ~211–256 bhp | ~275–306 bhp |
| Torque | ~440–480 Nm | ~600–700 Nm |
| Typical Fitment | Discovery 4, L405, L320 | L494, L405, Discovery 5 |
| 2025 Enquiries (engine) | 980 (combined with SDV6) [EM-VERIFIED] | 620 (508PS) [EM-VERIFIED] |
| Recon Engine S&F | £6,500–£9,500 | £8,000–£12,000 |
| Defining Failure | Crankshaft bearing (catastrophic) | Crankshaft bearing (catastrophic) |
| Best For | Budget-conscious buyers, older vehicles | Performance, towing, newer vehicles |
Enquiry volumes: TDV6 and SDV6 are often grouped together in our data under the 306DT engine code (980 enquiries). The SDV6 is also sold under the 508PS code for the 4.4 V8, but the 3.0 SDV6 is the more common variant.
The SDV6 is the better engine for buyers who can afford the higher purchase price. It produces significantly more power and torque, feels more refined, and is fitted to later, higher-value vehicles where the replacement cost is a smaller percentage of the vehicle's value. The TDV6 is still a capable, proven engine, but it's the older, lower-output variant, and the price difference at replacement time is smaller than you might expect. If you're on a tight budget, a well-maintained TDV6 can still be a great buy — just factor in the potential for a major engine repair.
The TDV6 was Land Rover's entry-level 3.0 V6 diesel, producing between 211 and 256 bhp depending on the application. It was fitted to Discovery 4, Range Rover L405, and Range Rover Sport L320. It's a proven, workhorse engine with good torque and decent fuel economy. However, it shares the same catastrophic crankshaft bearing risk as the SDV6, typically between 80,000 and 140,000 miles [PATTERN DATA]. At £6,500–£9,500 for a reconditioned replacement [EM-QUOTE], and with vehicle values often in the £6,000–£18,000 range, a major failure can easily exceed 60% of the vehicle's value, pushing it into scrap territory. For full details, see our 306DT Knowledge Centre and the 306DT failure page.
The SDV6 is the high-output version of the 3.0 V6 diesel, producing 275–306 bhp and significantly more torque (600–700 Nm). It was fitted to Range Rover Sport L494, Range Rover L405, and Discovery 5. The SDV6 is more refined, quicker, and better suited to towing and heavy loads. However, it shares the same crankshaft bearing risk as the TDV6 [PATTERN DATA]. At £8,000–£12,000 for a reconditioned replacement [EM-QUOTE], and with vehicle values typically £12,000–£55,000, the replacement cost is a smaller percentage of the vehicle's value, making it more likely to clear the 60% threshold. For full details, see our 306DT Knowledge Centre (both TDV6 and SDV6 share the same engine family).
The SDV6 is more expensive to buy but offers better performance. Running costs are similar, with the SDV6 being slightly thirstier but often more efficient in real-world driving due to its higher torque:
| Cost Area | TDV6 (306DT low-output) | SDV6 (306DT high-output) |
|---|---|---|
| Fuel Economy (official, combined) | ~35–40 mpg | ~32–37 mpg |
| VED (road tax, annual) | £280–£600+ (depending on year) | £280–£600+ (depending on year) |
| Routine Servicing (indie, annual) | £500–£800 | £500–£800 |
| Major Engine Replacement (recon S&F) | £6,500–£9,500 | £8,000–£12,000 |
| Insurance (group) | Group 45–50 | Group 45–50 |
Figures are indicative; actual costs vary by condition, mileage, and regional labour rates. The SDV6's higher replacement cost is offset by its higher vehicle value.
TDV6 — it's cheaper to buy, more common, and still offers excellent torque and fuel economy. Just budget for potential crankshaft issues.
SDV6 — the extra torque makes a real difference when towing heavy loads or driving fully loaded. It's the better engine for demanding use.
A well-maintained TDV6 can be a bargain, but set aside a £3,000–£5,000 emergency fund for potential repairs. If you can stretch, the SDV6 is worth the extra.
SDV6 — the higher vehicle value means the replacement cost is a smaller percentage, and the extra performance is a genuine benefit over the long term.
Both engines share the same catastrophic failure risk, so the decision comes down to performance needs and budget. If you can afford the SDV6, it's the better engine in almost every way. But the TDV6 is still a great engine if you're on a tighter budget and willing to accept the risk.
They share the same 306DT architecture, so they have the same reliability profile — both carry the same catastrophic crankshaft bearing risk. Neither is inherently more reliable than the other.
Yes — if you can afford it. The SDV6 offers significantly more power and torque, is more refined, and is fitted to higher-value vehicles where the replacement cost is a smaller percentage of the vehicle's value. For most buyers, the SDV6 is the better long-term choice.
The TDV6 is cheaper, at £6,500–£9,500 reconditioned supply and fit versus £8,000–£12,000 for the SDV6. However, the SDV6's higher vehicle value means the replacement cost is a smaller percentage of the vehicle's value.
It's theoretically possible but not cost-effective. The SDV6 has different turbos, injectors, and engine management software. It's cheaper to buy an SDV6 vehicle from the start than to try to upgrade a TDV6.
The SDV6 is better for towing, with its higher torque output (600–700 Nm vs 440–480 Nm). It makes a noticeable difference when pulling heavy loads or driving fully loaded.
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