I do not know any nice jQuery solution, so I provide low level javaScript way. Sorry for that, but believe it helps.
$("td").each(function(i,v){
for (var i = 0;i < v.childNodes.length;i++){
if (v.childNodes[i].constructor.name=="Text"){
v.childNodes[i].nodeValue=v.childNodes[i].nodeValue.replace(/BMW/,"Volvo");
}
}
});
Edit:
It's little bin incompatible so it's better version:
$("td").each(function(i,v){
for (var i = 0;i < v.childNodes.length;i++){
if (v.childNodes[i] instanceof Text){
v.childNodes[i].nodeValue=v.childNodes[i].nodeValue.replace(/BMW/,"Volvo");
}
}
});
Here I bring it to life: http://jsbin.com/ItotOPo/1/edit?html,js,output