Highlander specs says it has towing capacity of 5000 pounds; so it should be able to handle a 2500 - 3000 pound car?
The 2015 Highlander XLE AWD's “maximum trailer weight rating” is indeed 5,000 lbs. per SAE Standard J2807. However, this specification is not absolute, as there are several associated “ifs”, “ands”, or “buts”.
Specifically, owners manual page 209 includes this important note:
TWR (Trailer Weight Rating) is calculated assuming base vehicle with one driver, one front passenger, towing package (if available), hitch and hitch systems (if required).
In other words, if you want to "legally" tow a 5,000 lb. trailer, then there can't be many people or much stuff in the car.
Toyota's specifications for the Highlander XLE AWD verify this note. The GCWR is 9,900 lbs., and the curb weight is 4464 lbs. Assuming a 5,000 lb. trailer and a 50 lb. trailer hitch, that leaves 9,900 - 4,464 - 5,000 - 50 = 386 lbs. for the driver and a passenger and/or cargo. If you want to carry more passengers and/or cargo, then the trailer's weight must be correspondingly reduced.
There are also several important operational limitations. For example, Toyota says to not use the compact spare when towing (you'd need to consider buying and carrying a full-size spare), and the maximum trailer weight rating for an unbraked trailer is 1,000 lbs.
Uhaul's single-axle tow dolly weight 750 lbs and is unbraked. Following Toyota's guidance, this won't do for towing a 2,500 – 3,000 lb. car.
Uhaul's double-axle auto transport trailer is fitted with hydraulic surge brakes and weighs 2,210 lbs. Following Toyota's guidance, you
should be able to transport a car weighting up to 2,790 lbs. with this trailer after the Highlander is broken in
and if it's very lightly loaded. However, if you load up the Highlander with a bunch of people and/or stuff, then this combination wouldn't work.
I also recommend a thorough read of OM pages 206-223.
Finally, while I'm comfortable using my 3/4-ton pickup to tow a car on a transport trailer, it's not something I'd do with the Highlander.
HTH,
Jim / crewzer