Seat is offering up to £2,000 off its list prices during January.
It means drivers can buy a Leon Stylance 1.9 TDI for £13,220, down from the previous price of £15,220.
The offer also applies to the Altea Stylance 1.9 TDI, all-wheel drive Altea Freetrack 4 2.0, Altea XL Stylance 1.9 TDI , and seven-seat Alhambra Stylance 2.0 TDI.
Seat hope the discounts will draw customers away from the Ford Focus, Vauxhall Astra and Renault Megane.
A Ford Focus Zetec 1.8 TDCI has an RRP of £17,861, a Vauxhall Astra Design 1.7 TDCI costs £18,330 and a Renault Megane Dynamique 1.5 dCi £16,488.