The new Leon ST launches with the Ecomotive diesel engine with just 85g/km CO2, delivering best-in-class fuel economy of just 3.2l/100km in the NEDC and class-leading CO2 emissions along with stronger RVs than its direct competitors.

Meanwhile the new Leon TGI showcases SEAT’s compressed natural gas (CNG) technology. The newly developed 1.4-litre direct injection, turbocharged engine can run on either petrol or CNG, giving it outstandingly low running costs. In pure CNG mode, it’s capable of more than 400 kilometres, with an average fuel consumption rating of 3.5 kg of CNG per 100 kilometres. This equates to 94g/km.

In petrol mode, the engine provides an additional range of more than 940 kilometres. With the two CNG tanks (located beneath the luggage compartment) and the 50-litre petrol tank completely full, the Leon TGI achieves a theoretical range of nearly 1,400km.

A further environmental benefit of CNG is the reduction in airborne greenhouse gas emissions: CNG can reduce nitrogen oxide emissions by more than 85% and helps to reduce CO2 emissions by 24%.

The engine in the Leon TGI also gives outstanding performance, despite its fuel-efficiency. The unit delivers 110hp, with maximum torque of 200Nm available from 1,500 rpm. The 0 to 100km/h time is 10.9 seconds with a top speed of 194km/h.

Production of the five-door Leon TGI has already started, with the ST version to follow later in 2014.

SEAT added that the new products make it well placed to continue its recent strong growth in true fleet sales. In 2013 the Spanish brand saw sales grow by 43% in Germany, Spain, UK, France and Italy, compared to 2012.