Disney CRO has car rental deals, so I assume MS also has some. However, I've found that almost any time I check out a "deal" on a rental car, I'm paying more than I could have paid without the "deal."
I travel quite a bit, and here's the strategy I use.
First of all, a car is a car is a car. There is no difference between a Thrifty Neon and an
Avis Neon. It's a car. There are two things that flow from that realization:
1) it doesn't matter a bit who you rent from, and
2) you must compare car to car, not category of car to category of car. The latter one is because some companies call a particular model a "compact" and another company may call exactly the same car a "mid-size" and charge more for it. Or less.
Second, get familiar with the various travel sites on the WWW. I like Expedia, Travelocity is good, there are lots of them. Pick several and compare prices. I have invariably found the lowest prices on these sites,
not through airlines, hotels, travel clubs, etc.
Third, after you enter your requirements and get a list of available cars and prices, look for the little place that says "Sort by." That first list you are getting is sorted by how much the various car agencies PAID to be listed that way, not by anything that matters to you. So, find "Sort by" and
click on "sort by price."
Once you sort by price, amazing things happen. Tiny cars become expensive and mid-sized cars are often priced lower than economy cars. Sort by price. Then rent from the cheapest, or the one who offers more of what you want.
If you qualify for a senior citizen rate, you might check that, but be sure to compare it to the regular prices. I usually find the "senior discount" is
more than the regular price with rental cars -- don't know why.
Once you reserve your car, go to that rental car company's website and sign up for their customer loyalty program. It's free, and it will save you time at the rental counter. You'll also get offered upgrades at the counter, and those are often very good deals.
Company sites also offer "discounts" for their club members, but frankly I've always found those either the same as I was paying or more.
Shop carefully, be a smart consumer, and have a great trip!