Prioritised Shipping - Pay for Quicker Delivery, Free Shipping takes longer

Hi all,

Found this forum while searching for answers/studies on this, unable to find any discussion/answers online.

The website I deal with is an online car parts retailer that sells in UK and Ireland mostly.

We currently offer free shipping on all orders over €20 and the average order value is roughly €60.

I believe this model of free shipping is unsustainable in the long run due to rising prices. I would like to bring in priority shipping similar to the way Amazon/ASOS do it, where the customer pays ~€5 for a 2 day shipping service and can have the product delivered for free if they are willing to wait 3-5 days.

You can see how ASOS handle it here:

Have any of the other users here got any experience in this method of shipping? Has the rise in revenue from shipping offset the rise in basket abandonment?

Thanks for any help,
Max