I notice that you are currently running a promotion on fuel http://www.tesco.com/groceries/zones/default.aspx?name=petrol-promotion
This promotion will be a cost to the company that is paid by all customers, yet it is only drivers who stand to gain from it. As someone who regularly cycles to your store I think this is unfair. Why should I subsidise cheap fuel for drivers, drivers who frequently abuse and/or intimidate me due to my choice of transport?
If you insist on offering discounts on fuel then I think you should also offer free coffee and doughnuts to people arriving on bicycle or foot.