Mostly the safety and power accessaries. We have grown used to having our conviencies and they add weight. The cars of today have almost 1/2 more weight added than the cars of the 60s and 70s.The sound systems and extra tube routing for AC in those places we want to be comfortable at. Computorized everything and them talking to one another. So when you add all this up it comes out to be quite porkly. But the HP has increased to the 60s and 70s standard with a whole lot better gas mileage. The ride is better and our comfort is improved quite nicely.