With so little start-up money I think that whatever you earn is going to end up having to go back into the business, which is going to greatly limit what you can put in your pocket. Running power equipment on customer's properties without insurance is foolish and irresponsible in my opinion. Also, you will need to at least have a rider on your insurance policy to use your personal vehicle for business use...otherwise if you have a claim while using it for work your insurance company will likely deny it. Also, the lawn care season is longer than the typical college break...it starts while you're still in school and ends after you're back in school.
Instead of what you have planned, this is what I recommend. Skip the mowing and concentrate on general yard work that can be done with limited equipment and without a long-term committment. Stuff like hedge trimming, weeding and mulching requires little equipment and you can fit everything you need in your current vehicle. You can have mulch delivered or haul it in bags in the trunk. If you buy it in bulk you can transport it in 5 gallon buckets if you can't fit a wheelbarrow in your car. You can add things like window washing, deck staining and other services that also require little equipment. Bascially you can work as a domestic-type employee for people helping out around the yard. There are a lot of senior citizens who need a little extra help and are sympathetic to college students. You won't be able to charge as much, but your expenses will be way lower and likely put more money in your pocket. What I described is what my college-age son did last year working out of his Miata and it worked out well for him. He did borrow our station wagon a few times as well and it did help that I was able to send some customers his way. They in turn referred him to friends and neighbors.