Think I can help you with this. We have a Kia Ceed CRDi which is, as you probably know is a Hyundai i30 with different body. OK, its an estate and its just over 3 years old but its still relevant. We also have a 6 month old Seat Leon 1.4 TSi.

Both are great cars and have their plus points.

The Kia is more economical and is probably a bit better for space.

The Seat is way quieter and the TSI engine is really responsive but very economical for a petrol. The interior materials are better in the Seat as well and I think the Seat has a better ride but is not by much.

With your use the DPF on the Hyundia would not be an issue, ours does a regen every 250 to 300 miles.

Both are good choices, I would have either again without hesitation.

As Skidpan says, it'a a choice between two good cars: I assume that for whatever reason you don't want a petrol Hyundai. You're choosing between space and comfort (Hyundai) and something a bit livelier to drive (SEAT).

The Hyundai has a longer warranty, but it doesn't cost much to extend the SEAT's. I think that what would sway it for me would be that you can afford the SEAT new: you can then run it in yourself without the risk that a previous owner either sold it prematurely because it gave problems, or drove it like the clappers - or both. It could also have been a hire car.

If you find the Hyundai suits you better, there may be some good deals on a new one which could bring it down to costing little or no more than the SEAT.