The scale of road vehicles in the pakset is, unfortunately, inconsistent with the standard scaling that has been adopted for water, rail and tram vehicles. (Some of the rail vehicles are also not consistent with this scale, but I have slowly been working on that and intend to continue to do so). Road vehicles being inconsistent with rail vehicles or water vehicles might just about be passable, but being inconsistent with trams is unworkable.
To give an idea of the issue, see the below image, containing a tram to the standard scale, the existing Routemaster, and a Routemaster rescaled using the correct standard scale (including the 1.25x greater scale on the x and z axes than on the y axis):
As can be seen, the larger (original) Routemaster is noticeably too large in comparison with the tram (which is a relatively large tram from circa 1927):
The tram should be bigger than the 'bus, but, as can be seen, it is smaller than the larger (original) 'bus. The smaller (rescaled) 'bus is the correct size by comparison. To get to this correct size, I had to re-scale the .blend file by 0.75 on the y axis, 0.8 on the x axis and 0.81 on the z axis.
I am afraid that all the road vehicles in the pakset are almost certainly also incorrectly scaled by this degree. This includes all 'buses, lorries, trailers, traction engines, road horses, and private cars. It also affects industry graphics which have car parks with private cars parked in them and marked out parking bays (which will thus also be over-scale). I do not know how consistent that the scale of road vehicles is such as to know whether simply re-scaling all of them by the above factors will produce correct results, or whether it will be necessary to measure each vehicle individually. The former would be vastly quicker than the latter.
I should be interested in thoughts as to what is best to do about this. I think that we are probably inevitably going to have to re-scale all the road vehicles, which I am afraid will take rather a while.