You can get a diesel Sonic (Aveo) in Europe - a 1.3 L turbodiesel with a start-stop feature. I wonder what's the likelihood of GM offering a diesel for North America:
GM (N.A.) already confirmed they're going to offer a diesel option in the Cruze for 2013:
Source: GM News - United States - News2011-07-22 - DETROIT – Chevrolet confirmed today it will add a diesel variant to the Cruze lineup in North America in calendar year 2013. Diesel versions of the Cruze are currently being sold in Europe. Additional details on the Cruze diesel for North American markets will be released at a later date.
The diesel will bolster the already fuel-efficient Cruze lineup. Cruze Eco with a standard six-speed manual transmission, is the most fuel-efficient gas-powered/non-hybrid vehicle in America, with an EPA-rated 42 mpg on the highway.
So, yeah, pretty thin on details.
And we already know that such an engine would bolt right in the Sonic, because the 2 engines in the Sonic are already sourced from the Cruze: the 1.8L normally aspirated, and the 1.4 turbo.
I would say the answer will depend on 2 things:
1) The price of fuel.
Diesels cost more, and most people buy them for the increase in fuel economy (the fantastic torque is a nice byproduct of oil burners). North Americans have a demonstrated tendency to stop caring about fuel economy when high prices go back down (or when they get used to the higher prices).
GM will not go to the trouble of certifying/marketing a diesel if they're only going to sell 100 a month.
2) Marketing.
GM North America is flogging the Sonic as a fun car for the younger demographic. Sticking Herr Diesel's machina under the hood doesn't mesh with that marketing angle. Yet the 2012 Aveo will have a 1.3L turbodiesel in Europe, and it'll probably be the best engine (for performance and economy) and the most popular. (No 1.4 turbo petrol Europe version though.)
A diesel Sonic would make GM the only competition to the VW Golf diesel in North America.
But... if I had to bet, I'd say reason #2 makes it unlikely we'll see one on this side of the pond.
Does anyone even care? (Besides Rabbit?)