godmaster89

Well, you have a good point, but the thing is people want modded police cars so they can use ELS, if you can get LCPD: FR 1.0 with ELS 8 some modded police cars and maybe even the police helper all to work without crashing then we have something.

I highly recomend using a commandline, unless you have exceptionally high specs because Rockstar ripped GTA IV badly from console, to PC and it means the settings are all on exceptionally high, and can't be changed without it.
 
Once you've done that, then customize your graphics to your system.
 
Hope this helped.

And because of the gpu (video) and cpu you probably have the lag...
 
 
You can try a commandline (just Google it   ), or the other solution is to upgrade your system
 
 
*EDIT* LCPDFR doesn't affect it as much as car mods do

Make sure you don't have any big programs running in the background. 
 
Also, you can try and install a command line. download this http://www.gtagaming.com/downloads/gta-iv/misc-mods/11860 Then just plop it in the main directory