Road tax exemption and official fuel economy of 76.3mpg are the big selling points for the new Ibiza Ecomotive.
It is also better looking than its predecessor and has reduced noise, better interior and an improved specification.
It is expected to account for 10% of Ibiza sales, but currently counts for just under 5%.
Since going on sale in late spring, 507 Ecomotives have been sold, compared to 10,791 Ibiza units overall.
Seat said the five-door version of Ibiza has become increasingly popular; there has been a notable switch in demand from the three-door model.
Ecomotive buyers are “by their nature, pragmatic, practical people”, said Andy McGregor, Ibiza product manager.
“Customers are future proofing themselves,” he added.
Fleets will make up about 40% of sales.
Seat is also trying to appeal to older buyers. Unlike many manufacturers, its average buyer is in their 30s.
The VW Group-owned carmaker wants older generations who are “young at heart” to buy into the brand.
Main competitors are Ford Fiesta Econetic, Volkswagen Polo Bluemotion and Peugeot 207 Blue Lion.
McGregor said the car, which costs £12,205, still has a price premium for being sub-100g/km CO2, but with the benefits of this as well as fuel economy and good residual values, the outlay is worth it.
The car also has an affordable options list for dealers to upsell. This includes rear parking sensors (£147), alloy wheels (£289) and alarm (£152).