Updated again the stats in first post.

Most common makes:
4012 Ford
2590 Chevrolet
1389 Mercedes-Benz
1250 Renault
1028 Cadillac
1014 Citroën
1010 Volkswagen
944 Peugeot
876 Dodge
803 BMW
764 Volvo
562 Lincoln
558 Pontiac

Models: (a little biased as for some ones model field is not always the same for a similar model)
330 Ford Crown Victoria
323 Ford Mustang
308 Chevrolet Impala
272 Chevrolet Caprice
174 Mercedes-Benz S-Klasse
174 Lincoln Town Car
146 Ford Econoline
138 Cadillac Deville
135 Land-Rover Range-Rover
134 Mercedes-Benz
134 Ford Thunderbird
125 Lincoln Town Car Stretched Limousine
121 Chevrolet Bel Air
121 Jeep Cherokee

Chassis-codes:
276 Volkswagen Typ 1
84 Mercedes-Benz W220
83 Mercedes-Benz W126
79 BMW E30
73 Volkswagen Typ 2 / T2
69 Volkswagen Typ 17
65 Volkswagen Typ 2 / T1
62 Mercedes-Benz W140
59 Volkswagen Typ 14
53 Mercedes-Benz W115
52 Mercedes-Benz W116
52 BMW E36
52 Porsche 996
50 Volkswagen Typ 19E
49 Mercedes-Benz W123
48 Mercedes-Benz W124
48 BMW E34
48 Mercedes-Benz R107
46 Renault X48