Turbocharging makes engines more powerful by pushing more air into them, but the pushing and compacting of the air, also heats up the air — which is not desirable for combustion. To that end, the exhaust manifold and the turbine housing are cast in a one-piece, stainless steel piece — to displace more heat, and for increased durability.

Another novel aspect of the turbo unit is its motor-driven electrical waste gate, to precisely control boost pressure. The backpressure is reduced when turbo boost is not necessary by opening the waste gate, which improves fuel efficiency. In addition, during cold starts, the waste gate remains open, which results in faster engine warm up (less emissions).

The motor is hooked up to the same 6-speed automatic as the 2.4-litre Sonata. (Photo: Mike Goetz/Auto123.com)

Compact Powertrain
The motor is hooked up to the same 6-speed automatic as the 2.4-litre Sonata. Hyundai is one of only a few automakers to design and build its own 6-speed automatics, and designed this one to be very light and compact. Combined with the also light and compact 2.0-litre, makes for a very svelte powertrain — allowing Sonata to have a very stellar power-to-weight ratio of 5.5 kg per horsepower.

Satisfying Power Delivery
Only on the very brief run up to 2,000 rpm, does this engine feel somewhat different to a V6 of equal power. I think I still prefer how a big V6 smoothly dispatches those first few metres from a dead stop, but after that you would be hard pressed to tell the difference between this 2.0-litre I4 and various 3.0-plus-litre V6s on the market.

It feels lusty and luxurious in every driving scenario, but particularly excels when you’re already at highway speeds, and looking for warp speed to get around another vehicle, or just accelerating towards the horizon for the hell of it.

It transforms the rather, workman-like Sonata, into a machine you can have a lot of fun with. (It would be even more fun with a manual, which is not on offer).

Cabin Comforts
V6s are inherently smoother than I4s, particularly those equipped with an NVH-inducing turbocharger.

But I found the Sonata 2.0 Turbo to be very refined. Again, I’m pretty sure that in a blind taste test, most drivers would be hard pressed to identify this engine as an over-achieving four and not a V6.

I found the Sonata 2.0 Turbo to be very refined. (Photo: Mike Goetz/Auto123.com)