Can I substitute 合适 in place of 量身打造？
As lots of the comments have said, Yes, you can make the substitution, but that probably doesn't mean that you should.

The context is obviously an advertisement. It has psychology meanings between the lines. Using words like "Only for you" meant to make the targeted audience felt that they are special.  Of course, we do not really think a 50K RMB car is ONLY made for a special one, neither a $100K customised Tesla, unless it's the so-called Golden Rolls Royce (2.85 billion RMB). But everyone wanted to feel like being THE ONE, and that's why you probably should not replace 量身打造 with 最合适的代步车.