You know
how the numbers game works. If your car puts out 120g/km of CO2, your road tax costs £120 per year. One measly gram
less and you'll save £85. If you're driving, say, a sensible diesel Korean
hatchback and you're gentle with your right hoof, that's about 1,000 miles of
free driving.

Hyundai is playing cynical. By doing nothing more than
lengthening the gearing on the base-spec 1.6-litre diesel i30, the Koreans have
managed to improve consumption by a couple of mpgs and lower the CO2 output
from 125g/km to 119g/km. Or £85. Other manufacturers, VW and Seat, most
notably, have played the squeeze-the-family-hatch-under-120g/km game too, but
not quite so cynically. There are no clever aero revisions, no flush wheel
trims here. No eco-badging, either.

Bat-like sensibilities would be required to spot the longer
gearing. The greener i30 drives exactly like the base-spec diesel - indeed,
performance figures are unchanged. You know the story: it's a bit less fluent
on the road than the Golf, but it's a bit cheaper - the same as the standard
i30 diesel, in fact.

If you
really have the urge to Do Your Bit, take a look at lifetime environmental
impact, at NOX emissions, at recyclability. If you want to save a few quid
on your sensible diesel Korean hatchback - and give the taxman a cheeky stub in
the shin at the same time - this'll do just fine.