I find it interesting to drive low speed cars, it's a slightly different art to driving fast cars. It's quite easy, if you are driving on a flat course. If you are driving on a course with lots of gradient you really have to watch your gearchanges, and take extra care to keep as much momentum in the second half of the corner as you can. But really driving slow cars is all about keeping momentum. You can't be ragged like you can in higher powered cars.
When you are driving high grip, high powered cars, you have so much acceleration that you can quickly recover from a small loss in speed. You go more for the shortest route rather than the straightest route. In low powered cars the faster lines are often the ones that take you wider around the corner, that keep the speed up.
I think driving high speed/grip cars teaches you how to drive lower power/grip cars faster, but I imagine it doesn't usually work the other way round. When you change cars from a 787B to a Yaris it feels like everything is happening in slow motion - I guess it is. That's what I felt when, after spending all my time in GT3 driving 787Bs, Zondas and the like, I thought I'd give the Pro Vitz race a go. I never drove cars like the Vitz before, but I won every race in the championship on the first try. I just bought a 1.5 Yaris, tuned it to 272 hp, fitted some T6 soft tyres, and off I went. I didnt fiddle with the setup or anything, and it was just easy, I felt like I had an eternity to react to any little slide of the car. The only close race was Test Course because I had left the gearing as road gearing, and I had exactly the same top speed as the computer cars.
I think when you have dealt with a 900 hp monster, driving road cars close to the limit just follows easily, even if you have not done it before.