FuelMarble L — Fuel Efficiency Device for Fleets, SUVs & Heavy Diesel | Made in Japan
FuelMarble L — Fuel Efficiency Device for Fleets, SUVs & Heavy Diesel | Made in Japan
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| 🇯🇵 Made in Japan | ✅ JFTC Approved | 📦 Free UK Shipping | 🔄 30-Day Returns | 🛡️ DPF Protection |
🚛 Not sure how many units you need? See the FuelMarble Size Guide →
FuelMarble L is a Japanese-engineered fuel efficiency device for SUVs, HGVs, commercial fleets, and marine vessels. Drop it into the coolant reservoir. No tools. No mechanic. No engine modifications — and start saving on diesel permanently.
Verified by the Japan Fair Trade Commission (JFTC). Cleaner combustion means measurable fuel savings and longer DPF service life. Over 180,000 units deployed globally since 2002.
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Up to 15% Fuel Saving |
| 93% CO Reduction and 98% NOx Reduction |
| DPF Protection |
| Zero Maintenance Required |
What FuelMarble L Delivers:
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Up to 15% fuel efficiency gain — government-certified testing
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DPF protection — cleaner combustion extends filter life and reduces regeneration cycles
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93% reduction in carbon monoxide (CO) emissions — supports clean air zone compliance
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98% reduction in NOx and hydrocarbons (HC)
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Drop-in coolant reservoir installation — under 60 seconds per vehicle
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Zero maintenance — permanent device for the life of the vehicle
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Compatible with diesel, heavy fuel oil (HFO), and petrol engines
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No engine modifications — no impact on engine warranty
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For vehicles over 2 tons. For personal cars and vans, see FuelMarble S
Fleet ROI — 10 Truck Deployment Example:
10 trucks at 100,000 miles/year = £187,500/year in diesel
At 15% efficiency gain → ~£28,125 saved annually
Cost of 10 × FuelMarble L = £5,190
Estimated payback period: ~7 weeks
Based on 100,000 miles/year, 8 MPG, £1.50/litre diesel. Actual savings vary. See full fleet ROI breakdown
Protect Your DPF — Avoid £1,000–£3,500 Replacement Costs:
Diesel particulate filter replacement costs £1,000–£3,500 per vehicle. Across a fleet, premature DPF failures represent a significant unplanned cost. FuelMarble L’s cleaner combustion profile directly reduces the rate of DPF soot loading — extending service intervals and reducing the risk of blockage-related failure. Avoiding one DPF failure per vehicle per year covers the cost of FuelMarble L many times over.
View verified emission reduction data
How It Works (3 steps):
Installation — Under 2 Minutes:
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Open the coolant reservoir under your bonnet — the translucent plastic tank, not the fuel tank.
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Drop FuelMarble L inside and close the cap. No tools. No mechanic. No modifications.
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Drive normally. Most drivers notice improved fuel economy after 150–200 km as the coolant system reaches full operating temperature.
See the full step-by-step installation guide
Size Guide
| Vehicle Class | Size | Quantity | Note |
| Personal cars & vans | S | x1 | See FuelMarble S |
| 2-ton trucks / light commercial | L | x1 | This product |
| 4-ton to 13-ton | L | x2 | Order 2 units |
| Over 13-ton / marine | L | x3 | Order 3 units or contact us |
Product Specifications
| Product | FuelMarble L |
| Length | 220 mm |
| Diameter | 15 mm |
| Compatible with | SUVs, HGVs, fleets, heavy diesel, marine (over 2 tons) |
| Fuel type | Diesel, heavy fuel oil (HFO), petrol |
| Installation | Coolant reservoir - drop-in, no tools required |
| Maintenance | None - permanent device |
| Country of manufacture | Japan |
| Shipping | Free UK delivery |
| Returns | 30-day return window |
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Frequently Asked Questions
What makes FuelMarble L different from FuelMarble S?
FuelMarble L is larger (220 mm vs 130 mm) and is designed for vehicles over 2 tons — including SUVs, HGVs, commercial fleets, and marine vessels. It delivers the same core fuel efficiency and emission reduction benefits as FuelMarble S, with the addition of DPF protection through cleaner, more complete combustion. For personal cars and delivery vans under 2 tons, see FuelMarble S
How does FuelMarble L protect the DPF?
FuelMarble L improves coolant performance, stabilising combustion temperatures so fuel burns more completely on every engine stroke. More complete combustion produces less unburned soot — which is the primary cause of DPF loading. With less soot entering the filter, passive regeneration cycles handle the load naturally, DPF blockages become less frequent, and costly forced regen events and filter replacements are significantly reduced.
How many units does my fleet vehicle need?
One FuelMarble L covers vehicles up to 4 tons. Vehicles between 4 and 13 tons require two units; vehicles over 13 tons (heavy haulage, industrial machinery, and large marine engines) require three units. See the size guide above for the full breakdown, or contact our team if you’re unsure.
Is FuelMarble L suitable for my HGV fleet?
Yes. FuelMarble L is designed specifically for heavy-duty diesel applications including HGVs, lorries, and commercial fleets. It works via the coolant system and requires no engine modification, making it compatible with Euro V, Euro VI, and Euro VII-compliant vehicles. For volume pricing and fleet deployment support,contact our teamor visit the fleet page
Can FuelMarble L be used in marine vessels?
Yes. FuelMarble L is compatible with marine engines running on heavy fuel oil (HFO) as well as diesel. Its coolant-based mechanism works independently of the fuel type. Commercial vessel operators typically require three or more units depending on engine size.Contact us for a vessel-specific recommendation.
What is the ROI for a large fleet deployment?
A 10-truck fleet running 100,000 miles per year at 8 MPG spends approximately £187,500 annually on diesel. At a conservative 15% efficiency gain, that fleet saves around £28,125 per year. The cost of 10 × FuelMarble L units is £5,190 — giving an estimated payback period of approximately 7 weeks. DPF protection savings (£1,000–£3,500 per avoided replacement) add further ROI on top. See the full fleet ROI breakdown