CrunchSlaughtered
RPM Ruler
This is where the problem lays. VAG's big diesels are not good. And historically this comes from the shitty FWD longitudinal engine platform that AUDI still uses. The fact that the engine lays in front of the front axle prevents them from using an engine longer than an in line 5 cylinder. And because AUDI is developing the big diesels for VAG, they have to use V engines. Or with other words- they can not use the only suitable for big diesel type of engine: the inline 6. The problem with the V is that you have two banks. To use only one turbo you have to collect all the exhaust pipes but if the exhaust manifolds are on the outer side of the engine, this makes them too long, which causes turbo lag. and the engine can never have the response of the in line 6. One of the solutions to this is to use two turbos, one per cylinder bank of the same type. But this makes it more expensive, also another problem is the uneven firing per cylinder bank which makes the build up of pressure much slower and also massively shortens the life of the turbo bearing, because of the uneven impulses. Another solution to the same problem is to put the turbo in the hot V (between the banks), but the diesel engine has much worse thermal strain than the petrol one and this solution would require additional reinforcement that would again increase the cost. Then comes the variant of the diesel engines with sequential turbos. For the inline 6 it is as easy as a walk in the park, but because of the longer exhaust pipes this would not be very responsive in the VAG's engine. Of course solution to this problem is the replacement of the small turbo with and electrical one, that is undependable on the length of the exhaust pipes, but this again adds a huge amount of cost. So to compete against BMW's simple and light in line 6 with four turbos, they have to use much more expensive and heavier V8, that ruins the car's handling.Even the mighty v8 panamera diesel which I drove felt lacking.