Amazon-like "You Save"
Savings are important for customers. Showing only the old price and new is not enough as it requires customers to make mental calculations as to how much they are saving.
Amazon understands this - that's why it shows the savings separately http://www.amazon.com/dp/B00CX5P8FC/ref=br_imp_ara-1/179-1035819-2800748?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=desktop-hero-1&pf_rd_r=0YFM6R2R090AJAR40480&pf_rd_t=36701&pf_rd_p=2039920302&pf_rd_i=desktop
This is useful for many OpenCart installs as evidenced from my popular extension
I have already written the code and submitted a pull request that adds savings ($ and %) information below the price on the product page if a valid special price exists for the product.