If you're taking a trip on the Trans-Canada Highway, you may be doing it for the scenery & the experiences, as well as a way of saving money over flying, especially if travelling as a group or family.
Here are a number of tips to help you reduce your travel costs
Have a mechanic to look at your car before you go, and tune-up the engine, check tire pressure, change the oil, etcetera. Just the correct tire pressure can improve your fuel economy by 5%. By getting this work done by the local mechanic you know also save you the worry and hassle of a mechanical breakdown in an isolated location.
Driving at the speed limit minimizes gas costs, since speeding increases drag (it increases by roughly the square of the speed travelled!) and reduces fuel consumption. You also reduce the chances of an expensive speeding ticket. Avoiding travel during rush hour saves stop & start driving and car idling, which increase fuel consumption. If you're on vacation, sleep in a bit, or at least use the rush hour as a great time to have breakfast (in the morning) or do some sightseeing (in the afternoon).
Camping provides significant cost savings over hotel, motel, or bed & breakfast accommodation. Camping is also a great way to connect with other travellers, since you are separated by a fabric wall and a few metres, not a slab of concrete in a building. Get to know your campground neighbours, who may come from other countries or other parts of Canada. Most campgrounds are modern, with showers, good bathrooms, and recreational facilities. Sometimes, though, the weather does not co-operate and indoor accommodation is preferred, so you can consider a hostel (they are no longer called "youth hostels") or a cheap motel.
Canada has few toll-routes, but they do exist. BC's Coquihalla recently removed tolls, Nova Scotia has a short toll section, and around Toronto there is the 407. Ferries to Vancouver Island and to Newfoundland can add to your vacation costs. The Confederation Bridge to PEI has a toll only when leaving PEI but the Wood Island ferry charges in both directions.
Pack a cooler and a travel BBQ/hibachi, and shop in bulk along the way. Purchase the economy size and repackage into healthy portion sizes using re-isable plastic bags, which will last longer. Buying easy-to-cook healthy food also saves you from expensive fast food stops along the way. Shop for the fixings at a local deli/bakery and make your won sandwiches, instead of buying them from a sandwich shop. Don't forget the fresh fruit for snacking. There are lots of rest stops and picnic stops along the way where you can cook, or have a picnic.
Take advantage of free attractions and the scenery on your road trip. Your route will pass through or by many provincial parks, national parks, museums, festivals and fairs. Government-run Information/Rest Centres often have money-off coupons or free admission to attractions. They may also tell you when local attractions have discounted admissions. Plan your trip around "Open Doors" events when many or all local attractions are free. Students should have their student ID with them to qualify for any student/youth discounts. Some attractions offer discounts if you pay with a certain credit card or are a motor club member.