The motoring group has said the average price of a litre of petrol in the West Midlands fell by nearly 7p last month to 162.9p, but said the cut - the sixth biggest monthly drop recorded since 2000 - should have been bigger. The average price of a litre of diesel fell by 3.5p to 180.2p last month.
Drivers have again been urged to "shop around for the best deals" and not assume supermarkets offer the cheapest prices.
RAC fuel spokesman Simon Williams said forecourts should have been displaying prices around 152p with a profit margin of 7p, but RAC Fuel Watch data found some major retailers had margins of 17p per litre.
An examination of fuel prices around Shropshire has found that smaller, independent, garages are still offering the cheapest prices, far below the national averages for both petrol and diesel. Supermarkets - particularly Asda, Tesco and Sainsbury's - are offering some of the cheapest diesel prices, but none of them offer the best unleaded prices in the county.
These were the cheapest prices on Tuesday afternoon according to petrolprices.com.
Cheapest petrol around Shropshire
Essar Griffiths Garage, High Street, Leintwardine - 147.6p
Murco Four Crosses Filling Station, Holyhead Road, Bicton - 153.9p
Essar Grindley Brook Garage, Chester Road, Whitchurch - 153.9p
Essar The Mount Service Station, Shrewsbury - 154.9p
Texaco Hardings Garage, A490, Guilsfield - 154.9p
Essar Nesscliffe Service Station, Hollyhead Road, Nesscliffe - 155.9p
Texaco Robinson and Young Service Station, Shrewsbury Road, Wem - 155.9p
Texaco Mere Motors, Church Street, Ellsemere - 155.9p
Esso, Sycamore View, Prees Heath - 155.9p
Texaco, St Martin's Road, St Martin's - 155.9p
Texaco Stan's Superstore, Overton Road, St Martin's - 155.9p
Cheapest diesel around Shropshire
Essar Griffiths Garage, High Street, Leintwardine - 169.9p
Murco Four Crosses Filling Station, Holyhead Road, Bicton - 174.9p
Essar Grindley Brook Garage, Chester Road, Whitchurch - 175.9p
Essar The Mount Service Station, Shrewsbury - 175.9p
Texaco, Church Street, Bishop's Castle - 175.9p
Asda, Southwater Way, Telford - 176.7p
Asda, St Georges Road, Donnington - 176.7p
Shawbirch Service Station, Shawbirch Roundabout, Telford - 176.8p
Applegreen, A49 Crossways, Church Stretton - 176.8p
Tesco, Wrekin Retail Park, Telford - 176.9p
Sainsbury's, Colliers Way, Telford - 176.9p
Texaco, A489, Churchstoke - 176.9p
Co-op, Foldgate Lane, Ludlow - 176.9p
Co-op, High Street, Cleobury Mortimer - 176.9p
Texaco, Whitehall Bridge Street, Knighton - 176.9p