Does anyone else notice when you fill the car at shell the tank isn't as full as say sainsbury?

I only get 310 range on computer there against 350 with tesco. Or is it this just happens to me. Ford fiesta.

Nope, it's just you.

One thought. The Shell station may have faster or more sensitive pumps, or a different nozzle, that cut off sooner, so they aren't filling the tank quite to the top. The Tesco pump may put in a couple more litres of gas before it cuts off.

Instead of just measuring the distance, record how much fuel you add, and how far you travel, and see if there's a difference. You might find you only put in 31 litres @Shell, and 35l @ Tesco, in which case your fuel use is exactly the same.

All fuel pumps are slightly different, so will click off at slightly different levels of fuel in the car's tank.
They will also click off earlier if they are pumping more quickly.

A two-sided pump will often use the same motor to pump fuel to both sides, so will pump more quickly if there's no-one filling at the other side of the pump putting extra load on the motor.

Do you always use the same pump at each filling station? It might just be that the particular pump you tend to use at your local Shell filling station is particularly sensitive and fast compared to the pump you regularly use at the other filling stations.