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 3 Series (E21)
Table title:
Engines
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Model </th><th colspan=1 rowspan=1 > Years </th><th colspan=1 rowspan=1 > Headlights </th><th colspan=1 rowspan=1 > Engine </th><th colspan=1 rowspan=1 > Power </th><th colspan=1 rowspan=1 > Torque </th></tr>
<tr> <td colspan=1 rowspan=1 > 315 </td><td colspan=1 rowspan=1 > 1981-1983 </td><td colspan=1 rowspan=5 > Single </td><td colspan=1 rowspan=1 > M10 (M98) carb I4 </td><td colspan=1 rowspan=1 > 55 kW (74 bhp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 110 N⋅m (81 lb⋅ft) at 3,200 rpm </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=2 > 316 </td><td colspan=1 rowspan=1 > 1975-1980 </td><td colspan=1 rowspan=1 > M10 (M41) carb I4 </td><td colspan=1 rowspan=1 > 66 kW (89 bhp) at 6,000 rpm </td><td colspan=1 rowspan=1 > 123 N⋅m (91 lb⋅ft) at 3,000 rpm </td></tr>
<tr> <td colspan=1 rowspan=1 > 1980-1981 </td><td colspan=1 rowspan=1 > M10 (M118) carb I4 </td><td colspan=1 rowspan=1 > 66 kW (89 bhp) at 5,500 rpm </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 318 </td><td colspan=1 rowspan=1 > 1975-1980 </td><td colspan=1 rowspan=1 > M10 (M118) carb I4 </td><td colspan=1 rowspan=1 > 72 kW (97 bhp) at 5800 rpm </td><td colspan=1 rowspan=1 > 143 N⋅m (105 lb⋅ft) at 4,000 rpm </td></tr>
<tr> <td colspan=1 rowspan=1 > 318i </td><td colspan=1 rowspan=1 > 1980-1981 </td><td colspan=1 rowspan=1 > M10B18 injected I4 </td><td colspan=1 rowspan=1 > 77 kW (103 bhp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 148 N⋅m (109 lb⋅ft) at 4,500 rpm </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 320 </td><td colspan=1 rowspan=1 > 1975-1977 </td><td colspan=1 rowspan=6 > Twin </td><td colspan=1 rowspan=1 > M10 (M43) carb I4 </td><td colspan=1 rowspan=1 > 80 kW (107 bhp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 157 N⋅m (116 lb⋅ft) at 3,700 rpm </td></tr>
<tr> <td colspan=1 rowspan=1 > 320/6 </td><td colspan=1 rowspan=1 > 1977-1982 </td><td colspan=1 rowspan=1 > M20B20 carb I6 </td><td colspan=1 rowspan=1 > 90 kW (121 bhp) at 6,000 rpm </td><td colspan=1 rowspan=1 > 160 N⋅m (118 lb⋅ft) at 4,000 rpm </td></tr>
<tr> <td colspan=1 rowspan=1 > 320i </td><td colspan=1 rowspan=1 > 1975-1977 </td><td colspan=1 rowspan=1 > M10 (M64) injected I4 </td><td colspan=1 rowspan=1 > 92 kW (123 bhp) at 5,700 rpm </td><td colspan=1 rowspan=1 > 172 N⋅m (127 lb⋅ft) at 4,350 rpm </td></tr>
<tr> <td colspan=1 rowspan=2 > 320i (US) </td><td colspan=1 rowspan=1 > 1977-1979 </td><td colspan=1 rowspan=1 > M10B20 injected I4 </td><td colspan=1 rowspan=1 > 81 kW (109 bhp) at 5,700 rpm </td><td colspan=1 rowspan=1 > 152 N⋅m (112 lb⋅ft) at 4,000 rpm </td></tr>
<tr> <td colspan=1 rowspan=1 > 1980-1983 </td><td colspan=1 rowspan=1 > M10B18 injected I4 </td><td colspan=1 rowspan=1 > 74 kW (99 bhp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 135 N⋅m (100 lb⋅ft) at 4,500 rpm </td></tr>
<tr> <td colspan=1 rowspan=1 > 323i </td><td colspan=1 rowspan=1 > 1978-1982 </td><td colspan=1 rowspan=1 > M20B23 injected I6 </td><td colspan=1 rowspan=1 > 105 kW (141 bhp) at 5,800 rpm </td><td colspan=1 rowspan=1 > 190 N⋅m (140 lb⋅ft) at 4,500 rpm </td></tr>
</table>
Question:
What models were available at the E21 level?
Answer:
At the E21 level, three models were available: 316, 318 and 320.