Our spy photographers spotted a new Lotus undergoing testing but what model it is, exactly, remains a mystery. Lotus specialists say that the test vehicle is either the new Elise or Exige as the cars have been in production for seven and five years respectively.Our sources believe the new model could also be testing the new V8 engine for the 2011 Esprit. The new Esprit was due to feature either a BMW or Toyota V8, as the 3.5-litre V6 currently used in the Evora wasn't considered a viable option.Judging from our spy images, though, it seems the body of the Elise and Exige would be too small to fit a V8 engine. Currently. the Elise and Exige both run a 1.8-litre Toyota engine that might see an evolution in the future. We’ll keep you posted as we uncover more on this mystery Lotus.