I’ve just been going through a mortgage application recently and I didn’t see anything that related to the value of either property owned or the amount of any debt. All they were interested in was what the monthly repayments were for everything, including any other loans etc, and therefore whether you could afford the repayments on the mortgage. So having payments relating to a car would certainly impact what they were willing to lend, but it doesn’t seem like they’d actually care about the amount of the loan or the value of the property it was loaned for. In my case I don’t have another loans – quite the opposite as I own a house and several vehicles outright. That didn’t seem to be a factor (positive or negative) in the application process.
What I did find slightly annoying was that the affordability test came back as saying the minimum affordable term for the mortgage I was taking was 6 years, and the mortgage advisor seemed to have an issue at first with me not wanting to do that – but instead taking the mortgage over 20 years. It took several goes at explaining to him that I did actually want to have a life while I was repaying the mortgage, and not just be throwing every spare penny into it!