Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
BMW 5 Series (E12)
Table title:
Engines
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Model </th><th colspan=1 rowspan=1 > Engine </th><th colspan=1 rowspan=1 > Power </th><th colspan=1 rowspan=1 > Torque </th><th colspan=1 rowspan=1 > Years </th></tr>
<tr> <td colspan=1 rowspan=1 > 518 </td><td colspan=1 rowspan=1 > M10 (M118) 4-cyl </td><td colspan=1 rowspan=1 > 66 kW (89 hp) at 5,500 rpm </td><td colspan=1 rowspan=1 > 142 N⋅m (105 lb⋅ft) at 3,500 rpm </td><td colspan=1 rowspan=1 > 1974–1981 </td></tr>
<tr> <td colspan=1 rowspan=1 > 520 </td><td colspan=1 rowspan=1 > M10 (M17) 4-cyl </td><td colspan=1 rowspan=1 > 85 kW (114 hp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 162 N⋅m (119 lb⋅ft) at 3,700 rpm </td><td colspan=1 rowspan=1 > 1972–1977 </td></tr>
<tr> <td colspan=1 rowspan=2 > 520i </td><td colspan=1 rowspan=2 > M10 (M64) 4-cyl </td><td colspan=1 rowspan=1 > 92 kW (123 hp) at 5,700 rpm </td><td colspan=1 rowspan=1 > 172 N⋅m (127 lb⋅ft) at 4,350 rpm </td><td colspan=1 rowspan=1 > 1972–1975 </td></tr>
<tr> <td colspan=1 rowspan=1 > 96 kW (129 hp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 178 N⋅m (131 lb⋅ft) at 4,500 rpm </td><td colspan=1 rowspan=1 > 1975–1977 </td></tr>
<tr> <td colspan=1 rowspan=1 > 520/6 </td><td colspan=1 rowspan=1 > M20B20 6-cyl </td><td colspan=1 rowspan=1 > 92 kW (123 hp) at 6,000 rpm </td><td colspan=1 rowspan=1 > 160 N⋅m (118 lb⋅ft) at 4,000 rpm </td><td colspan=1 rowspan=1 > 1976–1981 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=2 > 525 </td><td class="highlighted"  colspan=1 rowspan=2 > M30B25 6-cyl </td><td colspan=1 rowspan=1 > 107 kW (143 hp) at 6,000 rpm </td><td colspan=1 rowspan=1 > 211 N⋅m (156 lb⋅ft) at 3,700 rpm </td><td colspan=1 rowspan=1 > 1973–1976 </td></tr>
<tr> <td colspan=1 rowspan=1 > 110 kW (148 hp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 208 N⋅m (153 lb⋅ft) at 4,000 rpm </td><td colspan=1 rowspan=1 > 1976–1981 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=2 > 528 </td><td class="highlighted"  colspan=1 rowspan=2 > M30B28 6-cyl </td><td colspan=1 rowspan=1 > 121 kW (162 hp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 234 N⋅m (173 lb⋅ft) at 4,000 rpm </td><td colspan=1 rowspan=1 > 1974–1976 </td></tr>
<tr> <td colspan=1 rowspan=1 > 125 kW (168 hp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 234 N⋅m (173 lb⋅ft) at 4,000 rpm </td><td colspan=1 rowspan=1 > 1976–1978 </td></tr>
<tr> <td colspan=1 rowspan=3 > 528i </td><td colspan=1 rowspan=3 > M30B28 6-cyl </td><td colspan=1 rowspan=1 > 129 kW (173 hp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 235 N⋅m (173 lb⋅ft) at 4,300 rpm </td><td colspan=1 rowspan=1 > 1977–1978 (US only) </td></tr>
<tr> <td colspan=1 rowspan=1 > 126 kW (169 hp) at 5,600 rpm </td><td colspan=1 rowspan=1 > 230 N⋅m (170 lb⋅ft) at 4,500 rpm </td><td colspan=1 rowspan=1 > 1979–1981 (US only) </td></tr>
<tr> <td colspan=1 rowspan=1 > 135 kW (181 hp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 235 N⋅m (173 lb⋅ft) at 4,200 rpm </td><td colspan=1 rowspan=1 > 1978–1981 </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 530 </td><td class="highlighted"  colspan=1 rowspan=3 > M30B30 6-cyl </td><td colspan=1 rowspan=1 > 130 kW (174 hp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 250 N⋅m (184 lb⋅ft) at 3,500 rpm </td><td colspan=1 rowspan=1 > 1975–1978 (South Africa only) </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 530i </td><td colspan=1 rowspan=1 > 131 kW (176 hp) at 5,500 rpm </td><td colspan=1 rowspan=1 > 251 N⋅m (185 lb⋅ft) at 4,500 rpm </td><td colspan=1 rowspan=1 > 1975–1978 (US only) </td></tr>
<tr> <td colspan=1 rowspan=1 > 530 MLE </td><td colspan=1 rowspan=1 > 147 kW (197 hp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 251 N⋅m (185 lb⋅ft) at 3,500 rpm </td><td colspan=1 rowspan=1 > 1976 (South Africa only) </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 533i </td><td class="highlighted"  colspan=1 rowspan=1 > M30B32 6-cyl </td><td colspan=1 rowspan=1 > 147 kW (197 hp) at 5,500 rpm </td><td colspan=1 rowspan=1 > 290 N⋅m (214 lb⋅ft) at 4,250 rpm </td><td colspan=1 rowspan=1 > 1979–1981 </td></tr>
<tr> <td colspan=1 rowspan=1 > M535i </td><td colspan=1 rowspan=1 > M90 6-cyl </td><td colspan=1 rowspan=1 > 160 kW (215 hp) at 5,200 rpm </td><td colspan=1 rowspan=1 > 310 N⋅m (229 lb⋅ft) at 4,000 rpm </td><td colspan=1 rowspan=1 > 1979–1981 </td></tr>
</table>
Question:
What is common  between the 525, 528, 530, 530i and 533i models of the BMW 5 Series (E12) ?
Answer:
The 525, 528, 530, 530i and 533i models of the BMW 5 Series (E12) were fitted with M30 six-cylinder engines.