| HPOF | Historical Preservation of Original Features | thru 1999 |
| DPC | Driver Participation Class | thru 1999 |
| 01A | 3-wheelers, Orient Buckboards & Cycle Cars | thru 1941 |
| 01B | 3-wheelers | 1942-1999 |
| 01C | Auto Red Bugs, Smith Flyers, Briggs & Stratton Flyers and similar vehicles | thru 1999 |
| 02 | High wheel (solid tire) buggy-type vehicles | thru 1919 |
| 03A | Electric vehicles | thru 1905 |
| 03B | Electric vehicles | 1906-1999 |
| 04A | Small vehicles, specifically named | thru 1941 |
| 04B | Small vehicles, specifically named | 1942-1999 |
| 04C | All Volkswagen vehicles | thru 1999 |
| 05A | Motorcycles | thru 1919 |
| 05B | Motorcycles | 1920-1945 |
| 05C | Motorcycles | 1946-1959 |
| 05D | All motorized bicycles & mopeds including Whizzer, Sportsman & Ambassador models | thru 1999 |
| 05E | Cushman Eagles | thru 1965 |
| 05F | All motor scooters and other 2 or 3-wheeled vehicles with small diameter wheels (ex. Mustang cycles) (all motorbikes with engine size 50cc must be street legal.) | thru 1960 |
| 05G | All motor scooters and other 2 or 3-wheeled vehicles with small dia. wheels (ex. Mustang cycles)(all motorbikes with engine size 50cc must be street legal.) | 1961-1999 |
| 05H | Motorcycles | 1960-1999 |
| 06 | Steam vehicles | thru 1905 |
| 07 | Steam vehicles | 1906-1914 |
| 08 | Steam vehicles | 1915-1929 |
| 09A | Gas vehicles, 1 cyl. | thru 1912 |
| 09B | Gas vehicles, 2 or 3 cyl. | thru 1913 |
| 10A | Ford Model T, brass radiator | 1909-1912 |
| 10B | Ford Model T, brass radiator | 1913-1916 |
| 11 | Ford Model T, steel shell radiator | 1917-1927 |
| 12 | Gas vehicles, not previously classified | thru 1905 |
| 13A | Gas vehicles, 4 cyl. | 1906-1909 |
| 13B | Gas vehicles, 4 cyl. | 1910-1912 |
| 14 | Gas vehicles, more than 4 cyl. | 1906-1912 |
| 15 | Gas vehicles, 4 cyl. | 1913-1919 |
| 16 | Gas vehicles, more than 4 cyl. | 1913-1919 |
| 17A | Gas vehicles, 2-wheel brakes, 4 cyl. | 1920-1929 |
| 17B | Gas vehicles, 2 wheel brakes, more than 4 less than 8 cyl. | 1920-1929 |
| 17C | Gas vehicles, 2-wheel brakes, 8 cyl. or more | 1920-1929 |
| 18A | Gas vehicles, 4-wheel brakes, 4 cyl. | 1920-1929 |
| 18B | Gas vehicles, 4-wheel brakes, more than 4 less than 8 cyl | 1920-1929 |
| 18C | Gas vehicles, 4-wheel brakes, 8 cyl. & more | 1920-1929 |
| 19A | Classic vehicles, specifically named | 1915-1931 |
| 19B | Classic vehicles, specifically named | 1932-1933 |
| 19C | Classic vehicles, specifically named | 1934-1936 |
| 19D | Classic vehicles, specifically named | 1937-1939 |
| 19E | Classic vehicles, specifically named | 1940-1948 |
| 20A | Production vehicles, (excluding Fords) | 1930-1931 |
| 20B | Production vehicles, (excluding Fords) | 1932-1933 |
| 20C | Production vehicles, (excluding Fords) | 1934-1935 |
| 20D | Production vehicles, (excluding Fords) | 1936-1937 |
| 20E | Production vehicles, (excluding Fords) | 1938-1939 |
| 20F | Production vehicles, (excluding Fords) | 1940-1945 |
| 21A | Ford Model A, open vehicles | 1928-1929 |
| 21B | Ford Model A, closed vehicles | 1928-1929 |
| 21C | Ford Model A, open vehicles | 1930-1931 |
| 21D | Ford Model A, closed vehicles | 1930-1931 |
| 21E | 4 cyl and V-8 Ford vehicles | 1932-1934 |
| 21F | 4 cyl and V-8 Ford vehicles | 1935-1937 |
| 21G | V-8 Ford vehicles | 1938-1940 |
| 21H | Ford vehicles 6 cyl. & V-8 | 1941-1948 |
| 22A | Commercial vehicles, load capacity under 1 ton | thru 1927 |
| 22B | Commercial vehicles, load capacity under 1 ton | 1928-1942 |
| 22C | Commercial vehicles, load capacity under 1 ton | 1943-1966 |
| 22D | Commercial vehicles, load capacity 1 ton & over | thru 1927 |
| 22E | Commercial vehicles, load capacity 1 ton & over | 1928-1942 |
| 22F | Commercial vehicles, load capacity 1 ton & over | 1943-1966 |
| 22G | Commercial vehicles, load capacity under 1 ton | 1967-1999 |
| 22H | Commercial vehicles, load capacity 1 ton & over | 1967-1999 |
| 22I | Military Vehicles | thru 1999 |
| 22J | Motorhomes | thru 1999 |
| 23 | Fire vehicles | thru 1999 |
| 24A | Competition (documented and pre-certified racing vehicles oval, circular or straight course) | thru 1999 |
| 24B | Competition (documented and pre-certified racing vehicles road, hill climb or gymkhana course) | thru 1999 |
| 24C | Competition (documented and pre-certified racing Motorcycles-all courses) | thru 1999 |
| 24D | Unrestored Race Vehicles (documented & pre-certified) (preservation awards only) | thru 1999 |
| 25A | Sports vehicles | thru 1960 |
| 25B | Sports vehicles - Open | 1961-1969 |
| 25C | Sports vehicles - Closed | 1961-1969 |
| 25D | Sports vehicles - Open | 1970-1999 |
| 25E | Sports vehicles - Closed | 1970-1999 |
| 26A | Production vehicles, (excluding Fords) | 1946-1947 |
| 26B | Production vehicles, (excluding 1948 Fords) | 1948-1949 |
| 26C | Production vehicles | 1950-1951 |
| 26D | Production vehicles | 1952-1953 |
| 27A | Production vehicles, (excluding 1955 Chevrolet) | 1954-1955 |
| 27B | Production vehicles, (excluding Chevrolet) | 1956-1957 |
| 27C | Production vehicles | 1958-1959 |
| 27D | Production vehicles | 1960-1961 |
| 27E | Production vehicles | 1962-1963 |
| 27F | Production vehicles | 1964-1965 |
| 27G | Production vehicles | 1966-1967 |
| 27H | Production vehicles | 1968-1969 |
| 27I | Production vehicles | 1970-1971 |
| 27J | Production vehicles | 1972-1973 |
| 27K | Production vehicles | 1974-1975 |
| 27L | Production vehicles | 1976-1977 |
| 27M | Production vehicles | 1978-1979 |
| 27N | Production vehicles | 1980-1981 |
| 27O | Production vehicles | 1982-1983 |
| 27P | Production vehicles | 1984-1985 |
| 27Q | Production vehicles | 1986-1987 |
| 27R | Production vehicles | 1988-1989 |
| 27S | Production vehicles | 1990-1994 |
| 27T | Production vehicles | 1995-1999 |
| 29 | Prestige vehicles, specifically named | 1946-1999 |
| 30A | Chevrolet Corvette | 1953-1962 |
| 30B | Chevrolet Corvette | 1963-1967 |
| 30C | Chevrolet Corvette | 1968-1977 |
| 30D | Chevrolet Corvette | 1978-1983 |
| 30E | Chevrolet Corvette | 1984-1999 |
| 31 | Ford Thunderbird | 1955-1957 |
| 32 | Chevrolet (excluding Corvette) | 1955-1957 |
| 34A | Ford Mustang | 1965-1966 |
| 34B | Ford Mustang | 1967-1970 |
| 34C | Ford Mustang, (including Mustang II) | 1971-1999 |
| 34G | Chevrolet Camaro (except High Perf.) | 1967-1969 |
| 34H | Chevrolet Camaro (except High Perf.) | 1970-1981 |
| 34I | Chevrolet Camaro (except High Perf.) | 1982-1999 |
| 35A | Designated Limited Production and Prototype vehicles | thru 1999 |
| 35B | Designated Limited Production and Prototype vehicles which do not meet criteria for 35A | thru 1999 |
| 35C | Pre-certified Second Generation Collector Vehicle (SGCV) | thru 1999 |
| 36A | Factory High Performance - Buick & Pontiac | 1957-1969 |
| 36B | Factory High Performance - Chevrolet & Oldsmobile | 1957-1969 |
| 36C | Factory High Performance - Chrysler, Dodge & Plymouth | 1955-1969 |
| 36D | Factory High Performance - Ford & Mercury | 1957-1969 |
| 36E | Factory High Performance - American Motors Corp. | 1960-1969 |
| 36F | Factory High Performance - Buick & Pontiac | 1970-1987 |
| 36G | Factory High Performance - Chevrolet & Oldsmobile | 1970-1981 |
| 36H | Factory High Performance - Chrysler, Dodge & Plymouth | 1970-1980 |
| 36I | Factory High Performance - Ford & Mercury | 1970-1980 |
| 36J | Factory High Performance - American Motors Corp. | 1970-1980 |
| 36K | Factory High Performance - Trucks | 1966-1989 |
| 36L | Factory High Performance - Buick & Pontiac | 1990-1999 |
| 36M | Factory High Performance - Chevrolet & Oldsmobile | 1990-1999 |
| 36N | Factory High Performance - Chrysler, Dodge & Plymouth | 1990-1999 |
| 36O | Factory High Performance - Ford & Mercury | 1990-1999 |
| 36P | Factory High Performance - Trucks | 1990-1999 |
| 36Q | Factory High Performance - Studebaker | 1955-1964 |
| 37A | Professional Vehicles - Ambulances, taxis, police cars, funeral vehicles | thru 1942 |
| 37B | Professional Vehicles - Ambulances, taxis, police cars, funeral vehicles | 1943-1999 |
| 38 | Sport Utility Vehicles | 1966-1999 |
| 39 | Special Interest Class - pre-certified (display only) | thru 1999 |