From a statement issued by the Ministry of Economy of El Salvador: 

The Ministry of Economy announced on June 6, that the reference prices for fuels, in force from 7 to 20 June 2016, will experience an increase in their prices. 
Nationally, new variations of the reference prices for fuels in the country are as follows: special gasoline a + $ 0.05 increase in the central and western parts of the country, in the eastern zones, an increase of + $ 0.04; regular gasoline a + $ 0.06 increase in the central and western parts of the country, in the east it will rise + $ 0.07; while diesel will increase + $ 0.08 in the three areas of the country. 

Variations in international prices of refined products (gasoline and diesel) in recent weeks have been influenced by a rise in prices in Central America, despite this, El Salvador is in second place with the lowest prices in gasoline and diesel in Central America. 

Average prices of gasoline and diesel (dollars / gallon)

Source: CentralAmericaData.COM

More on this topic

Central America: Fuel Prices up to March 25

March 2019

Price per gallon of regular gasoline: Nicaragua $3.72, Costa Rica $3.57, Honduras $3.44, El Salvador $3.22, Guatemala $3.15 and Panama $2.79.

From the statement of the Ministry of Economy of El Salvador:

The increase in reference prices for this fortnight is because gasoline inventories have experienced their largest decline since February until the last weekly report provided on Wednesday March 20 by the IEA.

Fuel Prices up to September 29, 2014

September 2014

Price of a gallon of regular gas: $3.75 Panama, $3.94 Guatemala , $3.98 El Salvador, $4.53 Nicaragua, $4.55 Honduras, $5.22 Costa Rica.

From a statement issued by the Ministry of Economy of El Salvador (Minec):

The Ministry of Finance announced on September 29th, new changes in reference prices for fuel, which will be in effect from 30 September to 13 October 2014.

Fuel Prices at the End of January 2014

January 2014

Prices of a gallon of regular gas: Costa Rica $4.85 , Nicaragua $4.50, Honduras $4.49 , Guatemala $4.18 and El Salvador $3.92.

nformation published by the Ministry of Economy of El Salvador (MINEC):

Reference prices for fuels from 21 January to 3 February

MINEC announces new variations on the reference prices for gasoline and diesel.

Gasoline Prices in Central America

November 2013

Price of a gallon of regular gas: Costa Rica $5.04, Nicaragua $4.36, Honduras $4.18, El Salvador $3.90 and Guatemala $3.84.

From data published by the Ministry of Economy of El Salvador:

Reference prices for fuel from 12 to 25 November

The MINEC has announced reductions in reference prices for fuels: up to - $0.11 on gasoline.