Jeeps aside, the OP started the discussion by asking about the best SMALL dingy cars. Personally, I wouldn't consider a 4000 lb vehicle small. My Ford Ranger only weighs 3600 lbs, but I don't think anyone except an F-150 owner would call it a "small vehicle". It certainly doesn't tow like a small vehicle.
Here's the list I considered over the past two years that I've been looking. Now that I bought a Smart, I wish I'd looked harder for that Mini Cooper roadster I really wanted. But you have to be careful with Mini's. The early ones had a problem with timing chain failure that wasn't solved until 2012. The Fiat is a better version of the "Smart", for a lot more money (and it's a Fiat). I REALLY wanted a '97 Chevy Tracker 4WD, but couldn't find a good one. The Toyota Yaris is probably the "best" of the lot, but very boring. I just couldn't make myself buy one. Maybe if they'd made a ragtop.
Smart (2008 to 2013) 1,808 to 1,896 lbs, 106.1" -- Towable as is without speed or distance restrictions.
Suzuki sidekick and variants (1989-2004) 2,291 to 2,751 lbs, 143.7" to 151.8" - 4WD STD towable, 2WD not (according to manual), but people have been doing it successfully for 20 years.
Suzuki X-90 (1995-1997) 2,326 to 2,469, 146.1" 12 ft -- STD is towable as is without restrictions. This was a roadster built on the Sidekick chassis. Even 4WD was available.
Suzuki Samurai (1986-1995) 2,059 lbs, 135" 11 ft. -- STD is towable as is without restrictions.
Mini Cooper (2001 present) 2,315 lbs, 142.8" 12 ft -- STD is towable as is without restrictions.
Hyundai Accent 2dr (2005-2011) 2,467-2,533 lbs, 159.3" 13 ft -- STD is towable as is up to 65mph
Mazda Miata (1990 present) 2,293 lbs, 155.4" 13 ft -- Not towable according to Mazda and REMCO but many people do (STD only).
Honda Del Sol (1992-1997) 2,295–2,535 lb, 157.6" 13 ft -- Honda says no but Suzuki says STD is
Honda S2000 (1999–2009) 2,809 lbs, 162.2" 14 ft -- Not towable
Toyota MR2 (1999-2007) 2195 lbs, 153 in 13' -- STD towable as is without restrictions
Toyota Paseo (1991-1999) 2025 to 2160 lbs, 164" 14' -- STD towable as is without restrictions
Toyota Yaris hatchback (2007-present) 2,290 to 2,335 lbs, 151" 13' -- STD towable w/o restrictions
Scion IQ (2008–2016) 1,896 lb, 120.1" 10ft -- Not towable
Scion xB (2003-2006) 2395lbs, 155.3" 13 ft. -- STD towable to 55mph and 200 miles
Scion tC (2004-2010) 2905lbs, 174" 15 ft. -- STD towable to 55mph and 200 miles
Scion xD (2007-2014) 2,665 lb, 154.7" 13ft (same as 4d Yaris)
Fiat 500 (2007–present) 1,907–2,161 lb, 139.6 in 12ft -- STD towable without restrictions
Kia Soul 2,714 to 2,837 lbs, 163" -- Kia says no. Lots of people do it anyway.
Honda Fit (2001-present) 2390 lbs, 151.4 in, 13 ft. -- STD towable up to 65mph
Honda Civic Coupe (2005-2011) 2,586 lbs, 175", 15 ft. -- STD towable as is without restrictions
Chevrolet Aveo (and Sonic) (2002-present) 2,546, 154" 13 ft -- STD towable as is without restrictions
Chevrolet Spark (Daiwoo) (2007-present) 2,246 to 2,312 lbs, 145 in, 12'-- STD towable as is without restrictions