[Savage GT]

I'd agree with most of what's said about Carrera cars. Would add that they seem to have licences for some makes that Scalextric struggle with (ie Ferrari)

On the subject of there performance, and acceleration out of a corner. Is it a case that the gearing is too high on them? I know their weight doesn't help. but would there be any way of lowering the gearing a bit, or is that hard to change?

I am fairly sure they are geared pretty much the same as Scalextric inline cars, usually 9/27 or 3.0:1.
Motors are probably similar to scalextric, maybe a little slower if anything.
It is the weight causing most of the issues, they use chunky thickness plastic and are over-engineered.

But as mentioned, race them like for like and all is well.

I only have 6 Carrera cars, 2 were lightly fettled as in shorter geared to help braking and changed wheels and tyres for Slot.it/NSR and some chassis weight.
These go well and race each other nicely.
The other 4 are subject to a little more involved modification, to fit long can motors for better torque to help braking and acceleration.
Again they won't be taking any performance crowns, but I buy them in pairs for a racing duo at home  .

As already mentioned some weight down low is always a great help.