Fuel Prices: Why They Go Up Fast… But Come Down Slowly

Lufop

Brent price vs diesel at the pump

For several weeks now, one question has been coming up repeatedly among drivers: why do fuel prices rise quickly… but never fall as fast?

In a context of tension on the oil market, this is not just a feeling — it is based on a well-documented economic phenomenon known as the “rockets and feathers” effect.

And today, the data observed in France clearly confirms this asymmetry.

📊 High prices despite falling oil

As of April 11, 2026, national averages remain high:

Diesel: €2.332/L
SP95 (Petrol): €2.056/L
SP98 (Petrol): €2.097/L
E10: €2.001/L

Source: data.gouv.fr – prix-carburants.gouv.fr (Open Licence Etalab 2.0)

At the same time, crude oil prices (Brent) have experienced periods of decline. Logically, pump prices should follow… but this only happens partially.

📍 Real example: a station in Gironde

Let’s take a real case observed on
Intermarché Saint-Symphorien (33113)

Diesel: €2.252/L (i.e. -3.4% below the national average)
SP98: €2.062/L
E10: €1.939/L

👉 This station is actually among the cheapest in its area, with a local price index of 20/100.

Despite this, prices remain high in absolute terms. And more importantly, they do not immediately reflect the drop in crude oil prices.

👉 View the station:
https://pompe.lufop.net/station/33/saint-symphorien/33113002

🚀🪶 The “rockets and feathers” effect: a well-known mechanism

This phenomenon was identified as early as the 1990s by economist Robert Bacon:

🚀 When oil prices rise → fuel prices increase quickly
🪶 When oil prices fall → fuel prices decrease slowly

Source: Bacon, R. (1991), “Rockets and Feathers” – Energy Economics

⚙️ Why does this asymmetry exist?

Several factors explain this gap:

1. ⏱️ Time lag effect

Fuel sold today was purchased, refined, and transported days or even weeks earlier. Distributors are therefore selling stock bought at higher prices.

2. 🛢️ Refining and logistics

The final price does not depend solely on crude oil, but also on:

refining
transport
distribution costs

Source: International Energy Agency (IEA), Oil Market Reports

3. 💰 Heavy taxation

In France, more than 50% of the fuel price is made up of taxes (TICPE + VAT).

👉 This mechanically limits the impact of falling oil prices on the final price.

Source: INSEE – Fuel price composition

4. 📈 Pricing strategies

Retailers often adjust prices faster upward than downward, depending on:

local competition
margins
demand

📉 A very real frustration for drivers

This mechanism creates a perceived imbalance:

Price increases are immediate and visible
Price decreases are gradual and discreet

As a result, even when oil prices fall, people feel that fuel prices remain stuck at high levels.

📊 What current data shows

Analysis of price curves over 30 to 90 days highlights:

A strong correlation between Brent and fuel prices
A time lag (several days delay)
An asymmetrical response (faster increases than decreases)

👉 Exactly what we are observing today.

🧠 Conclusion: a normal (?) phenomenon… but hard to accept

The asymmetry in fuel prices is neither a bug nor a recent anomaly: it is a well-documented economic reality for over 30 years.

But in times of energy crisis, it becomes particularly visible… and frustrating.

👉 As long as the market remains subject to these constraints (stocks, taxation, logistics), it is likely that:

price increases will remain rapid
price decreases will remain slow

A phenomenon that turns every trip to the pump into a daily economic barometer.

🔎 Track prices in real time

To monitor fuel prices around you and find the most competitive stations:

👉 https://pompe.lufop.net

Official data: prix-carburants.gouv.fr – updated daily

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