Google i20 and it tells you

carbuyer.co.uk/reviews/hyundai/i20/hatchback/engines#:~:text=Hyundai%20introduced%20a%20dual-clutch,car%20jerky%20at%20parking%20speeds.

The i20 1.4 came with a six speed gearbox. This engine was replaced in 2018(?) by two versions of a 1.0T in two forms 100bhp and 120bhp - the 120bhp has a six speed gearbox.

We had a 1.4SE for almost five years - just routine servicing done and no issues.

There was a facelift in 2018 which came with increased spec - safety kit, touch screen multimedia unit incl Android Auto/Apple Carplay, etc. Special editions such as the i20 Play have additional spec over the SE (sat nav, alloys from the Premium, privacy glass, two tone paint, etc), and are cheaper to buy. Currently got an i20 Play

Hi there SophieK, I have owned two i20s since 2011 and for relaxed motorway driving and brisk aceleration, I can definitely recommend any i20 model registered after September 2016, as long as you choose one with the 1 litre T-GDI engine. I assume your 2015 i20 Premium SE had the 1.2 litre engine, which I can say was briliant in my 'old' i20 but probably a little bit breathless in the later, larger and heavier New i20. The new 1.0 T-GDI engine, available in the New i20 from late 2016 onwards gives very quiet motorway cruising, excellent fuel economy if driven normally, and a very brisk turn of acceleration to keep most of those annoying 3 Series BMWs 'at bay' whenever you need it. The turbo charged one litre engine is very flexible and cruises quietly at around 2500 rpm at 70 mph in top (fifth) gear, which is 1000 rpm less and much more relaxed than the 1.2 litre engine spinning at around 3500 rpm at the same speed. So there is no need for a six gear in this car.

In short you should be able to fine a good used i20 1.0 T-GDI SE or Premium SE with anything from a '66 plate onwards, at a reasonable price, with the balance of its 5 year warranty still intact. Good luck and happy hunting :-)