No person generally cares if they receive a stack of cash (which is actually usually just a bank or certified check) or a different type of bank check (third party loan).
Negotiate. Get the best price. Call it cash. Then hand them your 1.8% third party loan check.
I don't understand why some are so scared of any kind of leveraging. It really is weak thinking.
Sure there is risk, that whatever you invest in will make less than ~2% loan rate (or even lose money). But if someone is worrying about losing 2%, then how can that person ever take a chance investing in anything? It is all a risk!
Be cold and logical and you will do just fine. You borrow when the risk is tolerable and you don't when it isn't. Leave the emotion out of it.
Do you think there is ever a point where arbitraging the interest rate vs potential market returns is just not worth it? Can I offer you an example?
Lets assume we are talking about financing $20K over 3 years at 2% vs investing it getting 8%.
The payment on a 3 year $20K 2% loan is $581.62/month
So I set up a spread sheet that went like this:
Month 1:
$20K invested at 8% gains interest of $133.33 for month 1. Total is now $20,133.33
Interest that accrued on the car loan at 2% for that month is $33.33
The loan of $20K increases by $33.33 increasing it to $20,033.33
You now pull out the car payment of $581.62 from you investment fund which now totals $19,551.71
I repeated this process for all 36 months. Arbitraging 6% will net you a little over $2000 profit over those 3 years. Now lets take into account that since the car is financed the loan company will demand a low deductible and higher damages than you would get on your own. Car insurance prices vary so lets just guesstimate that the price difference is $200 extra a year which I think is not too unreasonable. Now your profit margin is $1400 or $467 per year.
I agree that $467 is still $467 but now here is the big question for you to decide if it is worth it.
What if you have $50K in investments is $467 a year worth it? I would say maybe?
What if you have $100K in investments?
What if you have $500K?
What if you have a $1million?
What if you have $5 million?
As you can see at some point the $467/yr is just not worth it.
BTW, this is with a guaranteed 8% return. That is a pretty hefty number to guarantee. With a 6% return you are getting $1300 over 3 years minus costs or 700 over 3 years or $234/yr. is that worth it? To me I would rather be debt free than get an extra $234/yr. Actually I would gladly pay $234 every year to guarantee myself being debt free, and to not have that extra fixed expense in my budget.
What if you did this exactly 2 years ago with 1 more year to go? Well, If Vanguard Total Stock was your arbitraging investment of choice, you would be up $3.58% for both years and actually you are losing money on the deal thus far.