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50

diesel fuel cap

Worth a look

Shows a sweet-spot price point ($18.25 avg), but a small market ($53K/yr) keeps it on the watch list.

Market size 13Growth 21Conversion 62Competition 55Returns 66Price range 74Avg price 83Brand share 72Review moat 82Quality gap 50

Avg price

Great$18.25

avg listing price — sweet spot $15–$100

Review moat

Great369.48

avg incumbent reviews — the moat a new listing must climb

Price range

Good$7.48–$121.86

cheapest to priciest tracked listing — scored on the share inside $15–$100

Brand share

Good62%

top-5 brand share — brands hold most of the demand

Returns

Good2.4%

return rate — above 6% kills the launch gate

Conversion

Good5.5%

search→purchase rate — share of searches ending in a sale

Competition

Good52%

top-5 click share — leaders hold, buyers still browse

Quality gap

Good4.5★

avg incumbent rating — lower means beatable quality

Growth

Bad-7.8%

90-day search growth — must beat 0% to launch

Market size

Bad$53K

$53K/yr · 53K searches

Competition

The top 5 products take 52% of clicks — established leaders, but buyers still shop beyond them.

Brands

19 falling

Sellers

35

Top-5 brand share

62%

Open market

33%

  • Manymiba21%
  • YUESHAN15%
  • JOJOY LUX9%
  • Gates9%
  • Diesel8%
  • TINWID19195%

Product shelf

Each bubble is one product — market share against review moat; bubble size tracks estimated sales, color grades how beatable the incumbent looks.

0%4%$2K8%$4K12%$6K16%$8K101001K10K Reviews — right = deep review moat Market share (90d) ≈ est. sales
Beatable (≤4.3★) Contested Strong incumbent (>4.7★)

All 29 tracked products in this niche — three views at once, no toggling.

Demand & seasonality

Weekly Amazon search volume, last 104 weeks — -7.8% search growth over the last 90 days.
2K1KHoliday '24Spike '25Spike '26SepDecMarJunAugNovMarMay

No pronounced peak months · busiest ÷ quietest = 1.2×

Reviews

What buyers praise and complain about, mined from review topics.

What buyers love

Size-Overall47%

“Fit great”

Quality-Overall16%

“Good quality, easy installation”

Advertised Vs Actual Product7%

“works as it should”

Value For Money4%

“Worth the money”

Efficiency4%

“Works fine”

Magnetic Strength/Adsorption4%

“I also like that it is magnetic”

Fuel Efficiency3%

“Works great and covers fuel intake perfectly”

Ease Of Use3%

“Overall very easy to use”

Assembly/Installation2%

“Easy to install”

Ease Of Cleaning1%

“he loves that it helps keep the dust from the fill area”

What buyers complain about

Compatibility-Overall20%

“May not fit regardless of compatibility”

Size-Overall17%

“it doesn't fit my ball”

Quality-Overall14%

“Cheap made”

Advertised Vs Actual Product11%

“Did not fit my truck even though it said it would”

Durability7%

“Doesn't last”

Functionality-Overall4%

“Won't work”

Sensor4%

“This is not good for the truck as it will effect sensors”

Design-Overall4%

“Poor design do not purchase, Poor design, o-rings are the only thing holding this in place and they are not secure actually leaving crack”

Jamming/Clogging4%

“Yesterday, it was completely stuck, and I couldnt remove it from my Ram 3500 dually”

Ease Of Use2%

“it is hard to get off and back on”

Top return reasons

Size-Overall70%
Compatibility-Overall14%
Advertised Vs Actual Product3%
Mechanism Issues3%
Functionality-Overall2%
Defective Material/Parts2%
Magnetic Strength/Adsorption1%
Value For Money1%
Leak-Proof1%
Product Condition1%