My Name Is Earl
1973 Chevrolet El Camino (Earl's Truck)
Subaru BRAT (Joy's Truck)
Renault Le Car (Kenny's Hatchback)
Ford Tempo or Taurus (Teacher Earl)
2005 Dodge Neon (Seen in Christmas episode)
Ford LTD Country Squire (Barn Burner)
Yugo (Something to live for)
1980s Ford E-Series (Y2K)
1990s Chevrolet Suburban (Bounty Hunter)

Malcolm in the Middle
1980s Dodge Caravan
Dodge Dynasty (Seasons 1-5)
Ford LTD Country Squire (Pilot)
2000 Chrysler Concorde (Malcolm Babysits)
Various Porsches (Smunday)
Dodge Ram Van (Mr. Kenarban's car, season 2)
1967 Chevrolet Camaro (Malcolm's Car)
1960s Ford Mustang (episode w/ Laurie Metcalf)
Ford Tempo (Seasons 6-7)

Scrubs
Volvo Station Wagon (JD's first car)
Cadillac (Dr. Kelso's car)
Porsche (Dr. Cox's car)
Mini Cooper (Turk's car)
Ford E-Series Ambulance
2004 Nissan Quest (Turk and Carla test drive)

Two and a half men
Mercedes S-Class (Charlie's car)
Volvo V70 (Berta's car)

Monk
Volvo 740 (Sharona's car)
Ford Crown Victoria (Seen often)
Ford Taurus (Pilot)
Ford Taurus (Mr. Monk goes back to school)
Jeep Grand Cherokee (Natalie's car)
2004 Nissan Quest (Mr. Monk gets Cabin Fever)
2005 Ford Taurus (Mr. Monk bumps his head)
Ford Expedition (Mr. Monk and the Astronaut)
2006 Volkswagen GTI (Mr. Monk and the Actor)

Cash Cab (US version)
Toyota Sienna

Thanks, these will be added soon.
Though some are already listed (e.g. few cars from Monk)

Thanks, all shows added!

Here's one that I forgot:
My Name Is Earl
Cadillac Escalade ESV (Boogeyman)

Thanks.

That '70s Show is also missing.
The cars are:
Eric's: 1969 Oldsmobile Vista Cruiser.
Red and Kitty's: 1976 Toyota Corolla.
Hyde's 1967 Chevy El Camino.
Kelso has had three cars on the series, so far. A Dodge van, and a Volkswagen Samba Bus, both mid-'60s models. He currently (2005) seen driving an MG convertible.
Bob and Midge's 1970 Cadillac El Dorado (1998-2001)

Thanks