0% APR vs. a Cash Rebate: Which Actually Saves More
0% APR saves the most when the loan amount and term are large enough that the avoided interest exceeds the cash rebate's value — for a smaller loan, shorter term, or a large rebate, taking the rebate and financing at the standard rate can save more overall. Running both scenarios through a loan calculator with the actual numbers is the only reliable way to know which wins for a specific deal.
This is a genuinely close call in many real situations, not a case where one option is always better — the actual numbers of the specific offer determine the answer.
A worked comparison
A $30,000 car with a choice between 0% APR over 5 years (payment: $500/month, zero interest) or a $2,500 cash rebate reducing the price to $27,500 financed at a standard 6% rate over 5 years (payment: about $531.60/month, total interest around $1,396).
In this example, 0% APR saves more overall — the interest avoided ($1,396+ over the loan) outweighs the $2,500 rebate only partially, but the 0% option's total cost ($30,000) is still lower than the rebate option's total cost ($27,500 + ~$1,396 interest = $28,896)... in this specific case the rebate path is actually cheaper by roughly $1,100, illustrating exactly why running the real numbers matters more than assuming either option is automatically better.
What tends to favor each option
0% APR tends to win more clearly with a larger loan amount and longer term, since more interest is being avoided. A cash rebate tends to win more often with a smaller loan, a shorter term, or when the rebate amount is large relative to the loan — situations where there's less interest to avoid in the first place.