To determine the extent to which ENI S.P.A. should be advised to utilize hybrid bonds, we evaluate both the company's current capital structure and its broader financial profile against the provided S&P methodological guidelines.

**1. Calculation of the Current Hybrid Bucket:**
First, we identify the existing hybrid bonds in ENI's capital structure. According to the "Increase Decrease Through Net Issue Reimbursement Of Perpetual Subordinated Bonds Equity" line items, ENI issued €3.0 billion in 2020 and €2.0 billion in 2021. There were no new issues or reimbursements in 2022, bringing the total outstanding hybrid bonds to **€5.0 billion**. 

Next, we calculate the Total Adjusted Capital (TAC), which S&P generally defines as Total Equity plus Adjusted Net Debt:
*   **Total Equity (2023-01-01):** €55,230 million
*   **Gross Debt:** Long-term borrowings (€19,374m) + Current portion of LT borrowings (€3,097m) + Short-term borrowings (€4,446m) + Noncurrent lease liabilities (€4,067m) + Current lease liabilities (€884m) = **€31,868 million**
*   **Accessible Cash & Liquid Assets:** Cash and cash equivalents (€10,155m) + Current financial assets at fair value (€8,251m) + Other current financial assets (€1,504m) = **€19,910 million**
*   **Adjusted Net Debt:** €31,868m - €19,910m = **€11,958 million**
*   **Total Adjusted Capital (TAC):** €55,230m (Equity) + €11,958m (Net Debt) = **€67,188 million**

Dividing the outstanding hybrids by the TAC gives: 
€5,000 million / €67,188 million = **7.44%** 

This mathematical ratio lands virtually exactly on the **7.5%** target bucket.

**2. Qualitative Assessment:**
*   **Refinancing and Funding Needs:** ENI has moderate refinancing needs with approximately €7.5 billion in short-term debt and current portions of long-term debt maturing. The company also registered moderate acquisition activities (€1.6 billion in 2022).
*   **Leverage Metrics and Rating Headroom:** ENI's financial performance was exceptional in 2022 (Operating Profit of €17.5B, driven by high hydrocarbon prices), alleviating any severe leverage pressure. However, in the cyclical Oil & Gas (E&P) industry, maintaining the €5.0B hybrid layer meaningfully improves through-the-cycle adjusted leverage metrics and offers useful rating flexibility during downturns (as witnessed in 2020). 
*   **Cost of Debt:** Market conditions in 2022 indicate a steepening swap curve (the 5Y swap averaged 1.726%) and the sub-senior delta for non-financial IG issuers widened to roughly 2.30%. Consequently, maintaining or issuing hybrids only *slightly increases* the current cost of debt without being overly burdensome.
*   **No immediate scale-up required:** Due to their massive cash flow generation (FFO cash interest coverage is remarkably strong) and no "transformational" M&A pipeline requiring funding limits up to the 11.25% or 15% thresholds, scaling up the hybrid component is unnecessary. Correspondingly, a 0% recommendation is demonstrably incorrect given the already existent €5.0B in perpetuity issues.

Retaining the current composition perfectly satisfies the criteria corresponding to the 7.5% utilization threshold.

<answer>7.5%</answer>