GM graphic compares the Chevy Spark,released this week in the US, with the 1973 Impala.

Trying to get Americans, used to rumbling around in some of the biggest cars on the planet, into A-segment hatches such as the Chevy Spark - which was released on the US market this week - is like trying to get a live octopus into a milk bottle.

A slippery proposition.

So GM's marketing mavens came up with a graphic, comparing the Spark to the last Chev model released before the 1973 oil crisis, that year's Impala, a true aircraft-carrier of a car, nearly six metres long and in many ways the end of an era.

They pointed out that looks can be deceiving; today's cars are considerably better packaged than the sedans of the early 1970s so they're much smaller outside but designers are putting a lot more inside them than you might expect.

To start with, a Spark is half the length of the '73 Impala, but it's actually 150mm taller.

Both models run on 15” rims.

Now this you may find difficult to believe:

GM claims that front and rear headroom and front legroom are about the same on both cars, although the Impala has a clear advantage in rear legroom and all-round shoulder room.