Bought this car less than 30 days ago and it has very strong gas smell every time after refueling inside and outside the car...I have to leave my garage door open because of the strong gas fumes in the garage that also creep into the house!! *tr
2006 Mercedes-Benz CLS-Class fuel system problems
moderate 21 complaints filed with NHTSA · avg repair $1,200 · see fuel system across all vehicles →
Failure mileage
Complaints
21
Recalls
0
Avg fix
$1,200
When does it fail?
Of the 21 fuel system complaints filed for the 2006 Mercedes-Benz CLS-Class, here's the actual mileage breakdown — failures cluster heaviest at 75,000-100,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
Fuel system accounts for 19% of all owner complaints filed against this vehicle, across 7 categories tracked.
No new NHTSA fuel system complaint has been filed on this vehicle in over 12 years — the issue may be aging out of the active population.
The failure pattern owners describe
Buyer takeaway: A 2006 Mercedes-Benz CLS-Class fuel system has a pattern of leaking fuel from the sending unit, fuel tank seals, and related components, causing hazardous cabin odors and potential safety risks; even cars covered by recall #2008-020001 have experienced recurring failures. Budget for out-of-pocket repair costs if you purchase one of these vehicles, and inspect for persistent gasoline smell as a warning sign.
Owners of the 2006 Mercedes-Benz CLS-Class report a widespread fuel system problem centered on leaking fuel from the sending unit, fuel tank, and related fittings. The most common complaint is a strong gasoline odor inside the cabin, particularly in the rear seating area, that appears after refueling or during hot weather. When owners remove rear seat panels to investigate, they discover fuel pooling on top of the fuel sending unit or leaking from cracks in the unit's housing or plastic fittings. Fuel soaks into rear seat cushions and leaks underneath the vehicle, pooling where it's parked.
Recall #2008-020001, issued in 2008, aimed to address this problem but has proven ineffective. Owners report that Mercedes replaced the faulty sending units with identical units that subsequently failed the same way, leaving them facing $1,000–$2,000+ repair bills. One owner reported a stalled vehicle in traffic when the fuel gauge failed, and another described fuel leaking from a cracked fuel tank requiring full tank and seal replacement. Mercedes has declined warranty coverage for repeat failures, stating the recall repair was a one-time service. The persistent nature of these failures—reported across multiple model years and mileages—points to an unresolved design defect.
Failure modes owners describe
Fuel Sending Unit Cracking and Leaking
The fuel sending unit—located under the rear seat—develops cracks or failures at the top/housing area, allowing raw gasoline to leak onto and pool around the unit. Fuel accumulates on top of the tank, soaks into rear seat cushions, and allows fuel vapors to enter the cabin.
When: Variable; occurs after fill-up and worsens over time. Owners report issues from 48,000 miles onward; some within days of purchase or years post-recall.
Symptoms owners cite: Strong gasoline odor inside cabin, particularly in rear seating area; Overwhelming fuel smell after refueling; Gasoline odor intensifies in hot weather; Rear seat cushions soaked or damp from leaked fuel; Visible fuel pooling on top of fuel sender unit (underneath rear seat after panel removal); Fuel leaking underneath vehicle, forming puddles; Gasoline fumes in residential garage and creeping into home
Repairs/costs cited: Dealers typically recommend replacement of fuel sending unit and/or fuel tank. Owners report costs ranging from $1,000–$2,000+ for repair. Third-party repair shops have also performed the work.
Recalls/TSBs owners mention: Recall #2008-020001 was issued to address fuel sending unit issues and was performed on many CLS-Class vehicles (notably CLS550 and E-Class). However, owners report the recall failed to permanently solve the problem—defective units were replaced with identical units that subsequently failed again. Mercedes initially denied warranty coverage, claiming the recall repair was a one-time service and owners must pay out-of-pocket for repeated failures.
Fuel Tank Leaking from Seal Failure
Cracks develop in the fuel tank, often attributed to seal failure at the top of the tank. Fuel leaks from the tank interior and seeps into cabin and surrounding areas.
When: Reported at least twice in one year on one vehicle; timing not otherwise specified in narratives.
Symptoms owners cite: Strong fuel odor in cabin; Fuel fumes seeping into vehicle and upholstery; Visible fuel leaking from crack in tank; Gasoline smell persisting in seats even after repair
Repairs/costs cited: Service advisors noted requirement to replace fuel tank and fuel pump seals. One owner reported a dealership service advisor stated this was the second cracked fuel tank incident that year at their location.
Fuel Gauge Sensor Failure
Fuel sending unit/gauge sensor malfunction causes inaccurate fuel level reading on dashboard instrument cluster.
When: Recurring issue; one owner reported the problem occurring at least three times, with replacements by Mercedes dealership.
Symptoms owners cite: Fuel gauge reading incorrectly; Vehicle stalling unexpectedly due to false low-fuel reading (one report of stall in busy intersection with gauge showing 1/4 tank remaining); Persistent gasoline odor accompanying sensor failures
Repairs/costs cited: Mercedes dealership replaced the fuel module/sending unit multiple times (at least twice on one vehicle). Repairs did not prevent recurrence.
Recalls/TSBs owners mention: Mercedes performed replacements under dealership service, but permanent resolution was not achieved.
Plastic Fuel Pump Hanger Assembly Leaking
The plastic fuel pump hanger assembly or plastic 90-degree fitting at the pump connection develops leaks, allowing fuel to escape and pool on top of the fuel tank.
When: Identified after owner inspection following research into similar complaints.
Symptoms owners cite: Strong fuel odor after filling tank and during vehicle operation; Fuel leaking from plastic fitting and pooling on top of tank; Vehicle becoming unsafe to drive due to fuel escape amount
Synthesized from 21 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 3 most recent
After filling my car, I started smelling a gas odor coming from the driver side back seat area when I reach home about 2 miles away from the service station where I filled up. I figure the smell would have go away but everytime I drive my car I can be assured to smell that gas odor in the rear driver side passenger area which now is very annoying for a car I paid so much money for. .... *tr
Leaking fuel from crack in fuel tank. Service advisor at local Mercedes benz dealership states crack is from seal found on top of tank. Required replacing of fuel tank and fuel pump seals fumes from fuel seeped into vehicle and back seat cushions with very strong smell of fuel. Seats still smell like fuel, thus car with smell of fuel. Very uncomfortable with burning sensation to nose. Service…
Had fuel system trouble with your 2006 Mercedes-Benz CLS-Class?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the fuel system problem on the 2006 Mercedes-Benz CLS-Class?
It's a documented issue but not catastrophic. 21 complaints have been filed. Repairs average $1,200 and most owners catch it before it causes a breakdown.
At what mileage does the fuel system typically fail?
Across the 19 complaints that reported odometer mileage, most fuel system failures cluster between 57,790 and 78,510 miles, with the median around 65,000. A quarter of owners report trouble before 57,790; a quarter make it past 78,510. Maintenance history matters more than the odometer alone — this is the reported failure window, not a guarantee.
What does it cost to fix?
Independent shops typically charge around $1,200 for fuel system repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to fuel system?
No active recalls currently cover fuel system issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2006/Mercedes-Benz/CLS-Class.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.