When images of the Mk3 Prius leaked onto the internet, we weren’t impressed with what looked like an incoherent update of Toyota’s familiar and iconic humpbacked eco-whale.

Now that the covers have been literally whipped off the thing at the Detroit show, we’re more impressed with the design job. Not that we’ve managed to hop across the Pond for a proper look, but we have at least seen better pictures.

The headlamp area, for example, which looked a wibbly-wobby mess in the leaked photos, suddenly makes sense when seen from dead ahead. The side stance, as well, looks much better resolved that we’d expected, with a more cab-rearward feel than the Mk2. Toyota says the new Prius is the same height as the current model, and stands on the same wheelbase, but the top of the roof is about four inches further back.

This change is a surprise, given that Toyota says the drag coefficient is slightly better than the old model at 0.25 versus 0.26. Normally aerodynamicists prefer a bulbous front and tapered rear (as witness the obsessively slippery Aptera 2e with its tear-drop profile). This is the fruit of “more wind tunnel hours of testing than any other Toyota”, according to the firm, with particular attention being paid to under-floor airflow.

We’ve never seen an existing Prius with a sunroof, but the new model will offer one, which comes coupled with solar panels over the rear section of the roof. Energy from this panel is used to power a ventilation system designed to lessen heat build-up when the car is parked, meaning a more comfortable interior on summer start-ups and less fuel wasted powering the aircon. Heat from the exhaust system can also be fed into the heating system in winter - rather than relying on the engine coolant heat alone - with exhaust heat also helping to bring coolant up to temperature (and the engine up to peak efficiency) more quickly.

We’ve also now been able to have a better look at the Prius’s cheaper rival - the new Honda Insight - with pics of its rump revealing an eye-catching red bar linking the two rear lamp clusters.