Which Karcher Pressure Washer?

Hi guys,

I'm in the market for a PW and a Wet/Dry Vac. I checked out my local Wal-Mart and they carry the Karcher Pressure washers that suit my budget. I am wondering which in your opinions is the best valued model. Feel free to make other suggestions of other washers. I live in Canada so my options may be limited.

K2.25 w/ 1.3GPM and 1500 PSI @ $127 (link here)
K2.56 w/ 1.25GPM and 1600 PSI @ $157 (link here)
K3.67 w/ 1.5GPM and 1750PSI @ $175 (link here)

** Look on the right hand side of the page for product specs.

I'm only going to be using this PW for washing cars (mine and my small list of clientelle). I just need something that is going to get the job done. I'm not sure what the different features you need when selecting a PW so your advice is helpful.

Thanks,