Tesla challenger Rivian is postponing the construction of a factory in the US costing around $5 billion until further notice. The move will initially save Rivian $2.25 billion, company boss R.J. Scaringe said on Thursday at the presentation of new models. The new plant in the US state of Georgia was originally intended to build the cheaper future R2 electric SUV, which will now be produced at the existing plant in the town of Normal in Illinois instead. This will enable the model to be delivered more quickly. With a price starting at around $45,000 in the US, the R2 will be around $30,000 chea…