Scattered across my layout are a number of vehicles and besides the normal source of model vehicles in the UK there were/are two main sources that I use - the very old series of models given away at the Jet petrol/gas stations and the Kinder Surprise Models. A general problem is knowing whether a model is the right scale (I really wish all manufacturers show the scales of their models). A less important issue is the vehicle coming from the right historical period (1930's or earlier - happily the residents of my layout keep their vehicles for many, many years).

A useful web resource is the 1/87 Vehicle Club

Cars (Automobiles)

Jet Models
This was a series of nine model car kits in a range of scales thus:

As you can see the scales vary widely but several are close enough to HO to be used on my layout. Also, if anyone has wheel bases or lengths for the Renault. the Sunbeam and the Vauxhall let me know (all seem about HO). Serendipitously, these are made of styrene and so can be modified -  I used the Vauxhall to make a standard car and a Hansom Cab and the Ford to make a truck, a tractor and a Hucks Starter!

Kinder Surprise
As shown below there a large range of automobiles in various scales covering the pre-World War 2 years (veteran and vintage), the 1950's and later. The main problem I have is identifying the vehicles and would like some help with this and because of this I have included the Kinder Surprise model number. Also, some of the automobiles are bare metal and must be painted. I picked up my models for pennies at boot fairs (flea markets). Unfortunately, Kinder Surprise models are not available in the USA. The first part of the Kinder Surprise Number (tables below) is the year of manufacture. However as illustrated by the Duesenberg some models are reissued - originally issued in 1994 and reissued in 2001.

It is worth noting that some of the other Kinder Surprise models are usable on your layout (models like figures, animals, boats, planes and stuff that can be used). Useful pictorial lists for many Kinder Surprise models are Micks Model World and Thores Kinder Surprise.

Veteran Cars are perfect as they are from the period modelled. However, as the Kinder Surprise Cars are top end, they are only driven by the rich (GUM studios actors, motor racing drivers, airline passengers). The other residents own older (vintage cars).

1950s cars: Kinder Surprise also has produced som cars from the 1950's (below). Although they are not used on the layout, they are part of my collection.

Vintage Cars are somewhat early for my layout but as many of the "residents" are frugal and the local garages are skilled I had an excuse for using these models.

Modern Cars - Kinder has two grea Smart car models - fortwo coupe (TT93), forfour (TT91), fortwo crossblade ((TT92) and roadster coupe (TT90) - all around 1/72nd scale and so fine for OO scale but a bit large for HO and wrong period for me but cool.

Other Manufacturers
I also have models from other manufacturers spread around my layout.

Days Gone (Lledo): The disadvantage of this range is the fact that most are too large scalewise. But, having said that their double and single decker buses are just the right size and period. Additionally, I acquired a set of promotional historic racing cars (including Bluebird and the Railton Mobile Special) and as you see below some classic trucks from the Corgi - Days Gone collection. Alas, Days Gone do not specify the scales of their models.

The Lledo, Days Gone busses are as follows:

1931 AEC Renown Double Deck Bus (6 wheel): model length 3.65 inches, actual bus length 27 ft.

1932 AEC Regent Double Deck Bus (4 wheel): model length 3.4 inches, actual bus length 25 ft.

1932 AEC Regal Single Deck Bus: model length 3.6 inches, actual bus length 26.5 ft.

All of these are very close to HO scale (1/87th). The AEC Regent buses are a mixture of closed and open top. There are several bus companies on the layout. The two largest ones are Losea Transport (a play my view of London Transport) and Rather General (although these buses only show the name General). All the double deckers and some of the single deckers have advertisements - where appropriate the ordinal ones and some not. Where you wish to change the bus company name or advertisement this is easily done wiping down with cellulose thinner (but you can only do this as these models are metal with baked on paint).

Days Gone from Corgi have a range of classic trucks from the 1930s - as far as I can see scale wise these are some where between OO and HO. The range consists of several Sentinel Steam Waggons,  Dennis amd Foden. I changed upon them by accident and found that they were being sold off at £2.99 each rather than £5.99!

Matchbox: Over the years I have obtained several Matchbox models that are the right scale and period - including Showmen's Engines, a 1920 Preston Tram and a reissued farm tractor and a milk float. In the early days, the Matchbox catalogue showed each model's scale but this stopped (I wish that all suppliers showed the scale of their models).

Ahearn produce a neat range of HO scale John Deere equipment including several different tractors.

Jordan Products Highway Miniatures are a nice range of HO scale styrene vehicle kits from the right period.

Norscot have an interesting range of modern HO scale Caterpillar construction equipment models. (Alas too modern for me).

Micro Machines are generally too small but there are several that are ok - a farm tractor, a series of racing cars that I use as midget racers, small motor boats and some undersized vehicles that form part of a fairground ride.

delPrado again a chance find was a 1888 Ecelle "Rosalie" Gugumus (Horse driven escape ladder) - although it was a little over scale (1/73rd rather than 1/87th) I could not resist it. There are a lot of other fire vehicles in the range but either too large a scale or too modern for my layout

Roads

Obviously, vehicles must use roads and the table below is from Leeming E. L. (1924) Road Engineering Constable & Company Ltd., London : Bombay: Sydney (a book I picked up at a Scout jumble sale years ago).

Aircraft

Serene Aerodrome have several military and civilian aircraft all scaled about 1/100

Finding Scale

As I have mentioned many manufacturers do not show the scale of their models. This is further compounded by the fact that there may be insufficient information to identify the vehicle exactly and books about cars and other vehicles commonly do not show any physical dimensions (overall length and wheelbase).

If the model is from a regular manufacturer there is an online scale model database (although this does not include Lledo, Matchbox or my Kinder Surprise Models).

An example is how I found the scale for the Lledo buses. The first step in finding the scale of a model is to identify the vehicle make and model. With the Lledo buses this was quite straight forward from information on the web. But for some vehicles it is not so easy. For example for two of the 1950s Kinder Surprise Cars (the "blue" and "green" cars) I have not been able to identify the make and model.

Once you have determined make and model you can search for dimensions (overall length and/or wheelbase). But, unfortunately this information may be hard or impossible to find. It took me well over an hour to find the information about the Lledo buses and often I have to rely on the model looking right (eg Sumbeam Tourer) or wrong.

Once you have this information you can measure the model. I prefer using overal length to scale the model rather than the wheelbase. This is because the model manufacturer may have adjusted the wheel base to fit existing chassis tooling (I suspect that this is the case for several of the Kinder Surprise Vintage models). Also, length is a larger dimension and so provides a more accurate measure of scale. But, as early cars had a variety of bodies fitted on a standard chassis, wheelbase can be a better measure - for example the Ford Model T had a wheelbase of 100 inches. Another possible measure is track and a surprising number of early cars had a track of approximately 4ft 8.5 inches (16.5 mm in HO scale). Rather than using a rule, I prefer to use my digital calipers.

Another way of determining scale is where you have measurements of the same vehicle from another manufacturer in a known scale (eg OO Scale or 1/50th). For example having discovered by accident some Days Gone steam wagons (Sentinel and Foden) at a special price, I had the problem of finding the scale. For the Sentinel Steam Wagon, I compared its length with the 1/100th scale Matchbox model and for the Foden compared its length with a 1/50th scale model.