@mdevang , assuming that you are still looking for an answer here,
First Namaste;
Second , this is not the correct forum for answering questions regarding limitations ( or lack thereof ) placed by Immigration Services / DHS on H1-B visa holders; The volunteers are well versed in US taxes and/or the use of TurboTax to prepare the individual and business returns;
Third, however, I do not believe that there is any limitation for a H1-B worker to invest his earned ( and taxable ) income in any way he/she chooses to. Thus if you invest your earnings in securities etc. , it is your money and do as you please as long as you recognize the earnings and pay taxes on those. Ditto for renting your house or your car. At the same time, I shudder at the thought of somebody lending their car pout to a stranger without adequate self-protection ( insurance etc. ) even beyond what Tur offers. Suggest you talk to lawyer friend to make sure that you are protected. This country is full of trial lawyers ( nothing bad -- they are necessary ) and one can sue you to the hilt.
I wish you well and a very pleasant stay in this country
Namaste
pk
