Which is better, 1. TDI or 2. TDI?
The 1. There’s very little between the two on official combined cycle economy figures and both are in Band A for tax so running costs (other than insurance) are similar. A 2. L engine is indeed inherently superior to a 1. L engine in terms of its physical characteristics. The 2. L engine has a larger cylinder volume, meaning that in each intake stroke, it can draw in more air and inject more fuel for combustion, directly translating to stronger low-rpm torque and more abundant power.