This study presents a numerical investigation into the crashworthiness performance of thin-walled aluminum tubes reinforced with multi-cell ABS core structures under impact compression. Three core configurations were examined — group A, group B, and group C — each evaluated at four wall thicknesses ranging from 1.0 mm to 1.6 mm, yielding twelve specimens in total. Crashworthiness performance was assessed using five established indicators: maximum crushing load (MaCL), energy absorption (EA), specific energy absorption (SEA), mean crushing load (MeCL), and crushing load ratio (CLR). The results demonstrate that increasing wall thickness consistently improves MaCL, EA, and MeCL across all groups, although SEA exhibits a marginal decline at the highest thickness level in the groups A and B, indicating a mass efficiency limit. More critically, the number of internal ABS cells is found to be the dominant factor governing crashworthiness performance. The group C outperforms both the groups A and B across all metrics, as the 3-cell topology promotes uniform load distribution and stable progressive folding while suppressing premature collapse. The group B, despite its intermediate structural complexity, records the lowest SEA and CLR values among the three groups. Among all configurations, C4 achieves the highest performance, with a MaCL of 67.78 kN, EA of 2.46 kJ, SEA of 6.12 kJ/kg, MeCL of 27.35 kN, and CLR of 40.35%. These findings provide quantitative design guidelines for the development of lightweight, high-performance energy-absorbing structures in automotive engineering applications.