I don't think it can be smaller, because we need some performance, which means we need a certain size of engine. (evo.co.uk)
The overall size of the engine in these models will remain at the same 4.4 - liters, but the addition of BMW's Valvetronic variable valve timing is what gives this twin - turbo engine the extra punch it needs. (topspeed.com)
Great acceleration for size of engine / MPG with stick. (edmunds.com)