Cars in HL2 and their real-life counterparts as posted by FP users a while ago for reference:
(put in a drop-down so as not to flood the page)
Click to reveal
Here's a 'short list' of the make and model of the real life counterparts of every hl2 vehicle for future reference:
Avia A31
(https://dl.dropboxusercontent.com/u/1968768/889.jpg)
(http://slovenskainzercia.sk/x-sk/inz/814/814604-avia-a31-sklapac-r-v-1993-2.jpg)
Cadillac-Gage Commando V100
(http://img1.wikia.nocookie.net/__cb20090526231443/half-life/en/images/4/46/APC_green_model.jpg)
(http://www.fsmm.org/V100%20Exterior%20Front%20Right.jpg)
GAZ 24 Volga
(https://dl.dropboxusercontent.com/u/1968768/9cf803e0e8f4.jpg)
(http://gomotors.net/pics/GAZ/gaz-volga-24-01.jpg?i)
GAZ 53
(https://dl.dropboxusercontent.com/u/1968768/890.jpg)
(http://upload.wikimedia.org/wikipedia/commons/9/97/Gaz53_kirov.jpg)
Moskvitch 2140
(https://dl.dropboxusercontent.com/u/1968768/1530a1736a51.jpg)
(http://1.bp.blogspot.com/-q6K5F-TxRFE/Txr4ChLaOwI/AAAAAAAAAaY/tMqgI0649oY/s1600/moskvitch-2410-00.jpg)
RAF 2203 Latvija
(https://dl.dropboxusercontent.com/u/1968768/887.jpg)
(http://upload.wikimedia.org/wikipedia/commons/b/b4/Rafik_2007.jpg)
Skoda-Liaz 706 RT (Not 100% sure on this one)
(https://dl.dropboxusercontent.com/u/1968768/891.jpg)
(http://globalcarbrands.com/i/skoda/skoda-liaz-706-mt/skoda-liaz-706-mt-11.jpg)
Trabant 601 Universal
(https://dl.dropboxusercontent.com/u/1968768/896.jpg)
(http://upload.wikimedia.org/wikipedia/commons/5/5c/Trabant601K.jpg)
Volkswagen Golf II (Not 100% sure on this one)
(https://dl.dropboxusercontent.com/u/1968768/7b5540237079.jpg)
(http://photo.netcarshow.com/Volkswagen-Golf_II_1983_photo_02.jpg)
ZAZ 968 (This one I posted about a long time ago, Technically two cars
Front: ZAZ 968
(https://dl.dropboxusercontent.com/u/1968768/893.jpg)
(http://upload.wikimedia.org/wikipedia/commons/1/18/ZAZ-968_front.jpg)
Back: ZAZ 968M
(https://dl.dropboxusercontent.com/u/1968768/893%20%281%29.jpg)
(http://upload.wikimedia.org/wikipedia/commons/0/04/ZAZ-968M_on_Na_Gr%C3%B3dku_street_in_Krak%C3%B3w_(2).jpg)
Ultimately you can just save the names and google them when you plan to work on them.